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The 27th European Cosmic Ray Symposium (ECRS 2022) has been held in Nijmegen, the Netherlands from July 25th to 29th, 2022.
The European Cosmic Ray Symposium is covering the following topics in Astroparticle Physics:
Cosmic-Ray Physics,
Gamma-Ray Astronomy,
Neutrino Astronomy,
Dark Matter Physics,
Solar and Heliospheric Physics,
Space Weather,
Astroparticle Physics Theory and Models as well as
Experimental Methods, Techniques, and Instrumentation.
Proceedings are available at https://pos.sissa.it/423/
The scientific program will include invited plenary talks, contributed presentations, and poster sessions. There will be an award for the best poster.
All submitted abstracts will be reviewed by the ISPC. Presenting authors are expected to attend the conference (in-person or remote). A maximum of two contributions is allowed for each presenting author.
To upload your slides please go to the time table and select "detailed view". Go to your time slot. Click on your contribution. A window pops up. On the top right, you will see three stripes. Click on them to view the contribution details. This will bring you to the web page for your contribution. At the bottom, you see "Presentation materials". On the right hand side is a little pencil symbol. Click on the pencil symbol and upload your document. For oral contributions, please upload your slides in pdf format. For posters, please upload the poster in pdf format.
Important dates:
30 April 2022 end early bird registration
1 May 2022 end block reservation of rooms in conference hotel
29 May 2022: end abstract submission
12 June expect decision from ISPC concerning oral and poster contributions
25 June 2022 end online registration
25 July 2022, 9:00 on-site registration, conference starts
29 July 2022, 17:00 end of conference
Registration fee:
470 EUR regular registration
520 EUR on-site registration
50 EUR remote participation via zoom
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beneficiary name: Radboud University
IBAN: NL08 ABNA 0231 2478 34
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reference: 6201247 ECRS <participant name>
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Please specify the internal account number 6201247 and your name in order to correlate the payment with your registration.
We will offer a zoom connection for participants who cannot attend in person. There will be an in-person poster session. Posters should be A0 portrait format. Posters will be available on indico for remote participants.
We are looking forward to seeing you in Nijmegen
Jörg R. Hörandel on behalf of the International Advisory Committee, the International Scientific Program Committee, and the organizers
I was fortunate to attend the first European Cosmic Ray Symposium, held in Lodz, Poland, in 1968 during the Cold War. The meeting was organised by Arnold Wolfendale and Wlodzimierz Zawadzki to create an opportunity for cosmic ray physicists from the Western and Eastern blocks to meet. It was one of the most interesting scientific gatherings that I have ever attended. Through it, I made some important contacts and lasting friendships. I will describe some memories of the meeting and of a few of the other ECR Symposia that took place in subsequent years.
APPEC
In recent years, significant improvements in the sensitivity and image resolution of gamma-ray sky surveys provided by the current generation of ground-based particle detection arrays has led to groundbreaking discoveries. Among these discoveries are the detection of an unprecedented number of PeVatron candidates, multi-TeV gamma-ray emission associated with particle acceleration in the jets of a micro-quasar, and a new source class, gamma-ray halos, which are produced by electrons and positrons accelerating in the vicinity of pulsars, diffusing outside the classical pulsar wind nebulae, and then interacting with the ambient radiation field. In this talk I will cover the current status, latest results and future plans for gamma-ray astronomy with ground-based particle detection arrays.
The imaging atmospheric cherenkov technique was first established with the detection of gamma--ray emission from the Crab nebula by the Whipple collaboration in 1989. Since then, the technique has continued to advance dramatically, with the use of stereoscopic observations, fast imaging cameras and machine learning analysis techniques, rapidly transitioning from studies of individual gamma-ray sources to surveying regions of the sky. From just one source, well-over 200 TeV gamma-ray sources are currently known. More recently, observations of transient phenomena have risen to prominence, whilst recent advances in complementary ground particle detectors have further pushed the boundaries of the Imaging Atmospheric Cherenkov Technique towards high energies and extended sources. Nevertheless, the achievable energy and angular resolution is uncontested in the TeV energy range, enabling detailed studies of several complex regions.
This talk will review the Imaging Atmospheric Cherenkov Technique, highlighting some recent achievements by current generation facilities and providing an outlook to the forthcoming Cherenkov Telescope Array.
Corotating interaction regions affecting galactic cosmic rays are the origin of the 27-day GCR recurrence detected by neutron monitors on the ground, and in space, by spacecraft. The GCR recurrent variation during the solar cycles 24 and 25 based on the 3-d Parker transport equation is the subject of our studies. We investigate convection and diffusion effects on the structure of this variability. We present that the most realistic description of the heliospheric GCR transport gives combination of the temporal changes of heliospheric magnetic field strength and solar wind velocity incorporated into the mathematical modeling.
We present error estimation for the COR system dedicated to the cosmic rays trajectories in magnetosphere tracing available at cor.crmodels.ord and at GitHub https://github.com/COR-Cut-off-rigidity/Trajectories_IGRF_T04_C. Used numerical method is analysed and model dependence on crucial parameters is shown. The base error criterium to evaluate/determine model precision is defined.
For comprehensive global modeling of cosmic rays modulation in the heliosphere, it is essential to have a sound transport theory, and reliable numerical schemes with appropriate boundary conditions. For the description of the solar modulation process, and the propagation of the particles inside the heliosphere, Parkers transport equation is widely used. The correct and precise solution of this equation also must take into consideration errors. That’s why the presented work particularly focused on the estimation of the errors of the SOLARPROP model, based on the input parameters range, and statistical errors for these numerical solutions of 2D Parkers equation by stochastic differential equation method to suggest the safe simulation strategy for spectra evaluation at 1 AU.
The global neutron monitor (NM) network historically consists of over a hundred stations, that measure the galactic cosmic ray (GCR) flux all over the globe. This flux of GCR is modulated by solar/heliospheric magnetic activity, which is affected by the solar cycle and other solar activity manifestations. Thus, the temporal evolution of GCR flux can be ultimately used to study solar variability and probe the heliosphere. The combined measurements of the NM network can be viewed as essentially one huge spectrometer measuring the GCR flux, and they can give us considerable insights into the evolution of the heliosphere and the Sun.
We have used the recommendation list presented by Väisänen et al. (2020) to compile a combination of 147 NM stations. The result is separated into three different combinations according to the stations’ rigidity cutoffs, which depend on the geomagnetic shielding effect at the stations’ location. The high-statistics verified datasets will improve the quality and accuracy of the forthcoming studies based on these data.
A small local anisotropy of galactic cosmic rays (GCR) due to geometrical and orbital parameters is observed as a diurnal variability by the ground-based neutron monitor (NM) count rates. The capability of observing the GCR diurnal anisotropy is different for various NMs because of their different asymptotic directions. Here, we present the results of an analysis of the diurnal variability of polar NM count rates that varies from 0.16% to 0.4%. The only exception is the Dome C (DOMC) NM, which does not depict significant diurnal variation, it is only at the level of 0.03%. We interpret this fact to the polar, viz. off the equatorial plane, the asymptotic cone of DOMC NM restricted nearly to the South pole, with geographic latitude above 75 degrees. This determines the uniqueness of the DOMC NM station, which accepts cosmic ray particles originating from the off-equatorial region that is essential for a detailed study of near-Earth cosmic ray transport, in particular for the anisotropic solar energetic particle events.
For decades, the global neutron monitor network was successfully used to study cosmic ray variations and fluxes of accelerated solar ions, known as energetic solar particles. Recently, it has been used also for space weather purposes, specifically alerts and the related assessment of exposure to radiation. Here, we overview the current status and applications of the global neutron monitor network and discuss its capability to study solar energetic particles, namely assessment of their spectral and angular distribution, during ground level enhancements, focusing specifically on polar neutron monitors. Here we propose to build several new polar neutron monitor (NM) stations in order to optimize the capability of the spaceship Earth to register and provide reliable data for analysis of strong solar particle events, in the light of the possible closure of several stations. We propose to rebuild or open new stations in both the North and South hemisphere, e.g. Alert (ALRT), Heis island (HEIS), Summit station (SUMT), Kotelniy island (KTLN), Vostok (VSTK), Livingston island (LVGI), Barrow (BARW), Wrangel island (WRNG). We argue this proposal scientifically, while funding options need to be investigated.
The excess of gamma rays in the data measured by the Fermi Large Area Telescope from the Galactic center region is one of the most intriguing mysteries in Astroparticle Physics. This Galactic center excess (GCE), has been measured with respect to different interstellar emission models, source catalogs, data selections and techniques. Although several proposed interpretations have appeared in the literature, there are no firm conclusions as to its origin. The main difficulty in solving this puzzle lies in modeling a region of such complexity and thus precisely measuring the characteristics of the GCE. In this presentation I will show the results obtained for the GCE by using 11 years of Fermi-LAT data, state of the art interstellar emission models, and the newest 4FGL source catalog to provide precise measurements of the energy spectrum, spatial morphology, position, and sphericity of the GCE. I will also present constraints for the interpretation as dark matter particle interactions using the GCE, a gamma-ray analysis of dwarf spheroidal galaxies with LAT data and AMS-02 cosmic-ray antiprotons and positrons flux data.
The present work is dedicated to dark matter indiret searches and derived the robust constraints on annihilating WIMP parameters utilizing new radio observations of M31, as well as new studies of its dark matter distribution and other properties. The characteristics of emission due to DM annihilation were computed in the frame of 2D galactic model employing GALPROP code adapted specifically for M31. This enabled to refine various inaccuracies of previous studies on the subject. DM constraints were obtained for two representative annihilation channels: $\chi\chi \rightarrow b\overline{b}$ and $\chi\chi \rightarrow \tau^+\tau^-$. A wide variety of radio data was utilized in the frequency range $\approx$(0.1--10) GHz. As the result the thermal WIMP lighter than $\approx$ 72 GeV for $b\overline{b}$ channel and $\approx$ 39 GeV for $\tau^+\tau^-$ was excluded. The corresponding mass threshold uncertainty ranges were estimated to be (20--210) GeV and (18--89) GeV. The obtained exclusions are competitive to those from Fermi observations of dwarfs and AMS-02 measurements of antiprotons. Our constraints does not exclude the explanation of gamma-ray emission from outer halo of M31 and Galactic center excess by annihilating DM. The thermal WIMP, which explains the outer halo, would contribute about a half to the non-thermal radio flux in M31 nucleus fitting well both the spectrum and morphology. And finally we questioned the opportunity to robustly constrain heavy thermal WIMP with $m_x > 100$ GeV by radio data on M31 claimed in other studies. The talk is based on my paper ArXiv:2205.01033.
We present a thorough search for signatures that would be suggestive of super-heavy $X$ particles decaying in the Galactic halo in the data of the Pierre Auger Observatory. From the lack of signal, we derive upper limits for different energy thresholds above $\sim 10^8$ GeV on the expected secondary by-product fluxes from $X$-particle decay. Assuming that the energy density of these super-heavy particles matches that of dark matter observed today, we translate the upper bounds on the particle fluxes into tight constraints on the couplings governing the decay process as a function of the particle mass. We show that instanton-induced decay processes allow us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: $\alpha_X \approx 0.09$, for $10^{10} < M_X/{\rm GeV} < 10^{16}$. We show that this upper limit on $\alpha_X$ is complementary to the non-observation of tensor modes in the cosmic microwave background in the context of Planckian-interacting massive particles for dark matter produced during the reheating epoch. Viable regions for this scenario to explain dark matter are delineated in several planes of the multidimensional phase space that involves, in addition to $M_X$ and $\alpha_X$, the Hubble rate at the end of inflation, the reheating efficiency, and the non-minimal coupling of the Higgs with curvature.
We present a new reconstruction of the distribution of atomic hydrogen in the inner Galaxy that is based on explicit radiation-transport modelling of line and continuum emission and a gas-flow model in the barred Galaxy that provides distance resolution for lines of sight toward the Galactic Center. The main benefits of the new gas model are, a), the ability to reproduce the negative line signals seen with the H$I$4PI survey and, b), the accounting for gas that primarily manifests itself through absorption.
We apply the new model of Galactic atomic hydrogen to an analysis of the diffuse gamma-ray emission from the inner Galaxy, for which an excess at a few GeV was reported that may be related to dark matter. We find with high significance an improved fit to the diffuse gamma-ray emission observed with the \textit{Fermi}-LAT, if our new H$I$ model is used to estimate the cosmic-ray induced diffuse gamma-ray emission. The fit still requires a nuclear bulge at high significance. Once this is included there is no evidence for a dark-matter signal, be it cuspy or cored. But an additional so-called boxy bulge is still favoured by the data. This finding is robust under the variation of various parameters, for example the excitation temperature of atomic hydrogen, and a number of tests for systematic issues.
Among many earth-bound experimental attempts to detect dark matter (DM) particles, the DAMA/LIBRA experiment is the only one that has been claiming to observe the annual modulation of the event rate in the detector expected from DM in the Milky Way. The experiment is detecting the modulation signal for more than two decades with a statistical significance of 13.7 sigma. However, numerous null results of various other DM searches exclude the region of parameter space set by DAMA/LIBRA under standard assumptions. In order to resolve this decade-long tension, a model-independent validation must be performed using the same detector material: sodium iodide (NaI) crystals.
Cryogenic Observatory for SIgnals seen in Next-generation Underground Searches (COSINUS) is one of the several experiments designed to validate the DAMA/LIBRA results but is the only NaI-based experiment capable of identifying nuclear recoils on an event-by-event basis. With its low nuclear recoil energy threshold and the ability to discriminate between signal and background, COSINUS will provide a reliable comparison with DAMA/LIBRA.
Following years of research and development on prototype detectors, COSINUS is currently under construction at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. In our talk, we present the key features and challenges of COSINUS, including its current status and future goals.
The Baikal Gigaton Volume Detector is a neutrino telescope currently under construction in Lake Baikal. The main goal of Baikal-GVD is to detect high-evergy cosmic neutrinos using both track-like and cascade-like events. Baikal-GVD has been following the IceCube telescope neutrino alerts since September 2020. The prompt real-time response (the delay is ~ 3 min) to these alerts is complemented with offline search for coincidences in the time windows of +/- 1h and +/- 12h. If a coincidence is found, the potential signal is compared with the expected background and upper limits on the neutrino fluence are calculated.
Gamma-Ray Bursts (GRBs) are considered promising neutrino emitters. They appear as extremely intense bursts of gamma-ray radiation of extragalactic origin observed isotropically in the sky and constitute the most powerful explosions observable in the Universe. A lot has been learnt about these sources in the last years, however their jet composition remains still an open issue. Within the framework of the fireball model, mesons can be produced in photo-hadronic interactions occurring at internal shocks between shells emitted by the central engine. Then, if hadrons are accelerated from mesons decay, high-energy gamma rays and neutrinos are expected to be generated. By exploiting data collected by neutrino telescopes, temporal and spatial coincidences between high-energy neutrinos and GRBs can be searched for. In the context of identifying cosmic neutrino sources, an important role has been played over the last decade by ANTARES, the first undersea neutrino telescope located in the Northern hemisphere. Since investigations with ANTARES data have shown no coincidences so far, it was possible to set limits to the contribution of the detected GRB population to the diffuse neutrino flux measured by IceCube, as well as to the neutrino emissions expected from bright GRBs and from the recently detected emitting TeV GRBs. GRBs will be subject of investigation also for KM3NeT-ORCA and KM3NeT-ARCA, the next generation neutrino detectors under construction in two different sites of the Mediterranean Sea. Thanks to their geometry, both KM3NeT detectors will cover a broad neutrino energy range, from MeV to PeV, with a significant sensitivity improvement as compared to ANTARES. This will enable us to further investigate GRB emissions, providing new insights into their possible neutrino production. In this contribution, the results achieved over the last decade on GRB neutrino searches with ANTARES data are presented, as well as preliminary KM3NeT performances to detect such transient neutrino fluxes.
The main aim of the Baikal-GVD (Gigaton Volume Detector) neutrino telescope is to detect high energy astrophysical neutrinos and to identify their sources on the sky. The Baikal-GVD is located at a depth of 1366 metres in Lake Baikal. Currently (year 2022), it is composed of 10 functionally independent units, referred to as clusters, that comprise 2880 optical modules (OMs) in total. OMs are designed to register Cherenkov light originating from secondary particles produced in neutrino interactions.
Charged-current interactions of electron neutrino and neutral-current interactions of all three neutrino flavours produce a Cherenkov light signature of a single cascade in the telescope. Muons originating from the muon neutrino charged current interactions in the water induce track events.
Although, cascade topologies can also be created by discrete stochastic energy losses along the tracks from the atmospheric muon bundles. These muons represent the most abundant background in the search of astrophysical neutrinos via cascade channel. In result, different kinds of data analysis techniques for the selection of neutrino induced cascade events have been developed and optimized.
The techniques are based on the time and charge information of signals detected at the OMs (called hits). For instance, one of the technique searches the maximal number of track hits amongst cascade hits, which are present in the muon bundle event. Other techniques investigate the distributions of hits charges and positions of hit OMs associated with cascade events. All the presented selection tools were developed, tested, and optimized by means of the Monte Carlo simulations.
IceCube-Gen2-Optical is a planned large-scale upgrade to the existing IceCube Neutrino Observatory. This ~8 cubic kilometer in-ice detector is optimized for point-source science, yielding integer-factor improvements to angular resolution, and increased sensitivity to higher energies. Here, impact on future study of the diffuse astrophysical spectrum is presented. New analyses of upgoing muon neutrino tracks and of all-sky cascade events, are performed by adapting standard IceCube selection and analysis methods to this proposed configuration. Improvements to sensitivity of both analyses are discussed, along with the combined result. The all-sky cascade analysis excludes a majority of the parameter space allowed by the same period of IceCube observation. I explain the impact of leading atmospheric systematics on IceCube-Gen2 diffuse sensitivity, and on that of similar, future experiments. A characterization of the Gen2 optical and radio diffuse programs, and implications for the body of potential astrophysical sources in this coming era of next-generation, volumetric neutrino experiments, are provided.
In the ultra-high energy regime, the low predicted neutrino fluxes are out of reach for currently running neutrino detectors. Larger instrumented volumes are needed to probe these low fluxes. The Radio Neutrino Observatory Greenland (RNO-G) detects radio waves emitted by neutrino induced particle showers in the Greenlandic ice sheet. Radio waves have a large attenuation length in ice (O(1km)) and therefore RNO-G implements a sparse instrumentation to cover an unprecedented volume. The first three RNO-G stations have been deployed last summer and deployment will be ongoing in the next three years. This contribution introduces RNO-G, discusses lessons learned from the first year of data taking and outlines the reconstruction capabilities for the first neutrinos to be detected with the radio technique. Special focus is given on the method for directional reconstruction and the expected angular resolution.
Starburst galaxies (SBGs) and more in general starforming galaxies represent a class of galaxies with a high star formation rate (up to 100 Mo/year). Despite their low luminosity, they can be considered as guaranteed “factories” of high energy neutrinos, being “reservoirs” of accelerated cosmic rays and hosting a high density target gas in the central region. The estimation of their point-like and diffuse contributions to the neutrino astrophysical flux measured by IceCube can be crucial to describe the diffuse neutrino spectral features as well as the peculiar point-like excess like NGC1068.
To this aim we used the most updated gamma-ray catalog of this class of objects to perform a multimessenger study and describe their gamma-ray emission through a calorimetric scenario.
A whole sky analysis was performed through a blending of the measured spectral indexes and obtained a multi-component description of extragalactic background light (EGB), high energy starting events (HESE) and high-energy cascade IceCube data. Remarkably, we found that, differently from recent prototype scenarios, the spectral index blending allows starburst galaxies to account for up to 40% of the HESE events at 95.4% CL and favors a maximal energy of the accelerated cosmic rays at tens of PeV. The same calorimetric approach has been applied also to the known SBGs within 100 Mpc, considering, where possible, a source-by-source description of the star formation rate obtained from IR and UV observations. On this regard we showed how Future CTA measurements will be crucial to link the observed gamma-ray fluxes from resolved SBGs with their star-forming activity as well as to disentangle the cosmic-ray transport inside the core of these galaxies.
The expected neutrino emission, related to this scenario, are then compared with what IceCube and ANTARES have seen at TeV energies as well as with what can be expected from the incoming KM3NeT.
Thanks to tremendous experimental efforts, galactic cosmic-ray fluxes are being measured up to the unprecedented percent precision level. The logarithmic slope of these fluxes is a crucial quantity that promises us information on the diffusion properties and the primary or secondary nature of the different species. However, these measured slopes are sometimes interpreted in the pure diffusive regime, guiding to misleading conclusions. In this paper, we have studied the propagation of galactic cosmic rays by computing the fluxes of species between H and Fe using the USINE code and considering all the relevant physical processes and an updated set of cross-section data. We show that the slope of the well-studied secondary-to-primary B/C ratio is distinctly different from the diffusion coefficient slope, by an offset of $\sim 0.2$ in the rigidity range in which the AMS-02 data reach their best precision (several tens of GV).
Furthermore, we have demonstrated that none of the species from H to Fe follows the expectations of the pure-diffusive regime. We argue that these differences arise from propagation processes such as fragmentation, convection, and reacceleration, which cannot be neglected. On this basis, we also provide predictions for the spectral slope of elemental fluxes not yet analysed by the AMS collaboration.
Analysis of anisotropy of the arrival directions of galactic positrons and electrons has been performed with the Alpha Magnetic Spectrometer on the International Space Station. These results differentiate between point-like and diffuse sources of cosmic rays for the explanation of the observed excess of high energy positrons. The AMS results of the dipole anisotropy are presented along with the discussion of the implications of these measurements.
Precision measurements of cosmic ray positrons are presented up to 1.4 TeV based on 3.4 million positrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties are: (a) a significant excess starting from 24.2 GeV compared to the lower-energy, power-law trend; (b) a sharp drop-off above 268 GeV; (c) in the entire energy range the positron flux is well described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which dominates at low energies, and a new source term of positrons, which dominates at high energies; and (d) a finite energy cutoff of the source term at 887 GeV is established with a significance of 4.5σ. These experimental data on cosmic ray positrons show that, at high energies, they predominantly originate either from dark matter annihilation or from new astrophysical sources.
The fluxes and flux ratios of charged elementary particles in cosmic rays are presented in the absolute rigidity range from 1 up to 2000 GV. In the absolute rigidity range ∼60 to ∼500 GV, the antiproton and positron fluxes are found to have nearly identical rigidity dependence. In this presentation particular emphasis is made on new observations of the properties of elementary particles in the rigidity range above 500 GV.
The DArk Matter Particle Explorer (DAMPE) is a space-based particle detector launched on December 2015 from the Jiuquan Satellite Launch Center, in China and since then smoothly operating in a Sun-synchronous orbit. The main goals of the DAMPE mission include the study of the Cosmic-Ray Electron-positron (CRE) energy spectrum, the study of galactic cosmic-rays (CR), gamma-ray astronomy, and indirect dark matter search. The large acceptance and the detector figures make DAMPE able to measure the CREs and gamma-rays spectra up to few TeV, and cosmic-ray nuclei spectra up to hundreds of TeV, with unprecedented energy resolutions. This high-energy region is important in order to search for CREs sources, for dark matter signatures in space, and to have a better understanding of CR acceleration and propagation mechanisms inside the Galaxy. An overview of the DAMPE mission will be presented, along with main results and ongoing activities, with particular focus on CR spectral measurements.
Deuterons and ³He represent a few per cent of the cosmic-ray nuclei. They are mainly produced by fragmentation reactions of primary cosmic ⁴He nuclei on the interstellar medium and represent a very sensitive tool to verify and constrain CR propagation models in the galaxy, providing additional information to that of the cosmic B/C ratio. Precision measurements of the deuteron and ³He fluxes obtained with a high-statistics data sample collected by the AMS-02 aboard the International Space Station will be presented.
Beryllium nuclei are expected to be mainly produced by the fragmentation of primary cosmic rays (CR) during their propagation. Therefore, their measurement is essential in the understanding of cosmic ray propagation and sources. In particular, the ¹⁰Be/⁹Be ratio can be used as a radioactive clock providing the measurement of CR residence time in the Galaxy. In this contribution, the measurement of the ⁷Be, ⁹Be, and ¹⁰Be fluxes and ratios based on data collected by AMS are presented.
The Alpha Magnetic Spectrometer collected over 150 billion cosmic rays events during the first 8.5 years of operation aboard the International Space Station. A component of Z>2 ions with rigidities below the rigidity cutoff and located in the South Atlantic Anomaly have been measured both in the down-going and up-going direction.
After entering the Galactic cosmic rays (GCRs) into the heliosphere, their intensities decrease during their propagation toward the Earth. This effect is subjected to a variety of physical processes through their propagation which is referred to as CR solar modulation. The key ingredients in the study of this phenomenon are the knowledge of the local interstellar spectrum (LIS) of Galactic cosmic rays and the understanding of how solar modulation affects the LIS inside the heliosphere. For this purpose, here we present an improved data-driven description of the solar modulation phenomenon, that is, the temporal evolution of the CR flux inside the heliosphere caused by the 11-year variability cycle of the Sun’s magnetic activity. The model was applied to the Galactic proton flux measured by Voyager 1, AMS-02, and PAMELA missions which provide valuable information, allowing us to shed light on the shape of the LIS and the details of the solar modulation for the time period from mid- 2006 to mid-2017. The new results for the temporal dependence of the key model parameters, their relationship with solar activity proxies, the implications for the CR transport in magnetic turbulence, and the new insights into our understanding of the solar modulation effect are presented. The study of the time variation of GCR spectra observed on Earth can shed light on the underlying physical processes, specifically diffusion and particle drifts.
Similarly to the geomagnetic cutoff, which is the lower energy (magnetic rigidity) limit for particles that are able to pass the geomagnetic field and reach the Earth's atmosphere, there is the atmospheric cutoff. It represents the lower limit in energy for cosmic-ray particles propagating in the atmosphere and which can be registered on the ground by, e.g., neutron monitors. The atmospheric cutoff was previously estimated at the sea level as about 1 GV in rigidity, which is approximately 430 MeV in energy for protons. We calculated the atmospheric cutoff value for energetic protons over the range of altitudes from about 4500 m to 0 m above sea level, which corresponds to the depths from 600 to 1030 g/cm2, with: (a) Monte Carlo simulation of the cosmic ray cascade end (b) the altitude-dependent yield function of a standard neutron monitor 6NM64. The results agree with the earlier finding at sea level, though the yield function method shows more conservative, higher values of the cutoff compared to the cascade simulation method. It can be explained by the nature of the yield function, which takes into account the non-100% sensitivity of the detector to incident particles. Additionally, we calculated the effective atmospheric cutoff energies for two different conditions using the yield-function method, when only galactic cosmic rays are present, and when a strong solar energetic particle event happens. In this work, the case of GLE#05 was considered, which occurred on 23 Feb 1953. The resulting cutoff values for protons detected by polar neutron monitors are presented. It is shown that a strong solar energetic particle event can significantly reduce the atmospheric cutoff of a polar neutron monitor and the instrument is able to register particles with much lower energies than in the usual "galactic cosmic ray only" conditions.
Coronal mass ejections (CMEs), interplanetary shocks, and corotating interaction regions (CIRs) drive heliospheric variability, causing various interplanetary as well as planetary disturbances. One of their very common in-situ signatures are short-term reductions in the galactic cosmic ray (GCR) flux (i.e. Forbush decreases), which are measured by ground-based instruments at Earth and Mars, as well as various spacecraft throughout the heliosphere (most recently by Solar Orbiter). We recently developed an analytical model to explain CME-related Forbush decreases, using an expansion-diffusion approach (ForbMod, Dumbovic et al., 2018; 2020). The model takes into account the energy dependance of the detector with which the measurements are made. ForbMod is currently tested through model-to-observations comparison using SOHO/EPHIN and could ultimately provide a helpful tool to analyse Forbush decreases with various detectors. With new modelling efforts, as well as observational analysis we are one step closer in utilizing GCR measurements to provide information on CMEs, especially where other measurements (e.g. plasma, magnetic field) are lacking.
There are currently multiple available neutron monitor (NM) databases which host and distribute measurements of the total of 147 NM stations. These databases include the World Data Center for Cosmic Rays (WDCCR), the Neutron Monitor Database (NMDB), the Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation (IZMIRAN) and individual station/institution databases.
Upon further analysis of these datasets, it is evident, that in most cases the databases host different versions of the datasets for individual stations. This is very problematic for data users, who are not aware of differences in the datasets. It also puts the reliability and reproducibility of scientific results at risk, since analyses in different studies might operate with different versions of the data. Documentation of the datasets is often lacking, with procedures for correcting errors or other problems missing.
We have analysed the 1-hour NM measurements of 147 individual NMs to determine the recommended data sources to use for each station. These recommendations were constructed by selecting a baseline of long-lived good quality “prime” stations, to which the individual datasets were compared. During the study, the basic information of all the stations (latitude, longitude, rigidity-cutoff, etc.) was collected in a single excel file, freely available to all users.
We study the 27-day variations of galactic cosmic rays (GCRs) based on neutron monitor (NM), ACE/CRIS, STEREO and SOHO/EPHIN measurements, in solar minima 23/24 and 24/25 characterized by the opposite polarities of solar magnetic cycle. Now there is an opportunity to reanalyze the polarity dependence of the amplitudes of the recurrent GCR variations in 2007-2009 for negative A < 0 solar magnetic polarity and to compare it with the clear periodic variations related to solar rotation in 2017-2019 for positive A > 0.
We use the Fourier analysis method to study the periodicity in the GCR fluxes. Since the GCR recurrence is a consequence of solar rotation, we analyze not only GCR fluxes, but also solar and heliospheric parameters examining the relationships between the 27-day GCR variations and heliospheric, as well as, solar wind parameters.
We find that the polarity dependence of the amplitudes of the 27-day variations of the GCR intensity and anisotropy for NMs data is kept for the last two solar minima: 23/24 (2007-2009) and 24/25 (2017-2019) with greater amplitudes in positive A > 0 solar magnetic polarity. ACE/CRIS, SOHO/EPHIN and STEREO measurements are not governed by this principle of greater amplitudes in positive A > 0 polarity. GCR recurrence caused by the solar rotation for low energy (< 1GeV) cosmic rays is more sensitive to the enhanced diffusion effects, resulting in the same level of the 27-day amplitudes for positive and negative polarities. While high energy (> 1GeV) cosmic rays registered by NMs, are more sensitive to the large-scale drift effect leading to the 22-year Hale cycle in the 27-day GCR variation, with the larger amplitudes in the A > 0
polarity than in the A < 0.
The first solar proton event of solar cycle 25 was detected on 28 October 2021 by several neutron monitors (NMs) in the polar region as well as the fleet of space-borne instruments. It is identified as the GLE (ground-level enhancement) #73 in the International GLE database, with the strongest signal registered by the DOMC/DOMB monitors located at the Antarctic plateau at the Concordia French-Italian research station. Here, we report the observations and the study of this event using the global NM network and SOHO/ERNE records. We present the derived angular and spectral features of solar energetic protons, including their dynamical evolution throughout the event employing a state-of-the-art model based on analysis of the neutron monitor data. Discussion related to the prompt and delayed component of the GLE inducing solar protons is performed. Several applications of the derived results are discussed.
Since its launch, the Alpha Magnetic Spectrometer-02 (AMS-02) has delivered outstanding quality measurements of the spectra of cosmic-ray (CR) species (p¯, e±) and nuclei (H–Si, Fe), which resulted in a number of breakthroughs. Spectra of heavier low-abundance nuclei are not expected until later in the mission. Consequently, we exploited a “fraction” of HEAO-3-C2 data that match available AMS-02 measurements, together with Voyager 1 and ACE-CRIS data, to make predictions for the local interstellar spectra (LIS) of nuclei that are not yet released by AMS-02. The resulting H to Ni LIS, in the energy range from 1 MeV/n to 100÷500 TeV/n, cover 8÷9 orders of magnitude in energy. In this context, some peculiar excesses have been found, hinting at possible primary components. The observed excesses in Li, F, and Al appear to be consistent with the local Wolf-Rayet stars hypothesis, invoked to reproduce anomalous 22Ne/20Ne, 12C/16O, and 58Fe/56Fe ratios in CRs, while excess in primary Fe is likely connected with a past supernovae activity in the solar neighborhood.
Understanding how ultrahigh energy cosmic rays (UHECRs) reach energies in excess of 1e20 eV stretches particle acceleration physics to its very limits. In this talk, I will discuss how such energies can be reached, using general arguments that can often be derived on the back of an envelope. I will review possible particle acceleration mechanisms, with special attention paid to shock acceleration. Informed by the arguments derived in the talk, and with insights from Galactic CR acceleration in supernova remnants, I will then discuss which classes of astrophysical sources might be UHECR sources, including my own (biased) perspective. Aided by hydrodynamic simulations, I will show that shocks in the backflows in radio galaxies are good accelerators of UHECRs, then present simulations in which the jet flickers and explore the impact on the jet morphology. I will explore a scenario in which a significant fraction of UHECRs originate from local radio galaxies like Centaurus A and Fornax A, arguing that they can explain the observed UHECR anisotropies. Finally, I will highlight the importance of variability in these potential UHECR sources, and explore the intiguing possibility that the UHECR arrival directions are partly a result of "UHECR echoes" or "reverberation" from magnetic structures in the local Universe.
Large solar eruptive events, e.g. flares and coronal mass ejections, are capable of accelerating solar energetic particles (SEPs) to energies >300 MeV. These high energy SEP events are capable of causing disruption on Earth through ground level enhancements (GLEs). As such, the propagation of these particles towards Earth pose a significant space weather hazard. We explore past SEP events, both through 3D test particle simulations of particle propagation through the heliosphere and through analysis of SEP properties observed by GOES-HEPAD between 1984-2017. Our research suggests that features like the heliospheric current sheet are relevant to 71% of our historic events, and that the majority of GLE events have source locations close to the HCS. Other factors, such as flare and CME parameters, are compared to the observed SEP properties (e.g. peak flux and fluence). We find weaker correlations between peak fluxes and both flare intensities and CME speeds that is observed at lower particle energies.
In the last two decades, several techniques have been developed to predict the occurrence of Solar Proton Events (SPEs), which are mainly based on the statistical association between the >10 MeV proton flux and precursor parameters. In this framework, the Empirical model for Solar Proton Event Real Time Alert (ESPERTA) provides a prediction of SPEs after the occurrence of ≥M2 solar flares, by taking as input parameters the heliolongitude of the flare source region, the soft X-ray fluence and the radio fluence at ~1 MHz (Laurenza et al., 2009). In this work we reinterpret the ESPERTA model in the framework of machine learning and, we apply the rare events corrections (i.e. SMOTE oversampling as well as the modified class weighted loss function). We find that by applying a cut-off on the heliolongitude of ≥M2 solar flares, we are able to reduce the False Alarm Rate (FAR) of the model. The cut-off is set to E20°, where the cumulative distribution of ≥M2 SPE-associated flares shows a break, which reflects the poor magnetic connection between the Earth and the Sun for eastern events. The best performances are obtained by using the SMOTE algorithm, leading to Probability Of Detection (POD) of 0.83 and a FAR of 0.39. Nevertheless, despite the implementation of rare events corrections to the model, we demonstrate that a relevant FAR on the predictions is a natural consequence of the sample base rates. Indeed, from a Bayesian point of view, we found that the FAR contains explicitly the prior knowledge about the class distributions. This is a critical issue of any statistical approach, thus we discuss the importance of performing the model validation by preserving the class distributions within training and test datasets.
Systematic study of relativistic solar energetic particles provides key information about various processes, such as production and acceleration of energetic particles at the Sun and the interplanetary medium, interactions of energetic particles with magnetic fields in the heliosphere i.e. probing the electromagnetic and plasma conditions of the heliosphere, assessment of their terrestrial and space weather effects.
Following solar eruptive processes, such as solar flares and/or coronal mass ejections solar ions are accelerated to a high-energy range. In the majority of cases, the maximum energy of the accelerated solar ions is several tens of MeV/nucleon, but in some cases, it exceeds 100 MeV/nucleon or even reaches GeV/nucleon range. In this case, the energy is high enough, so that solar ions generate an atmospheric cascade in the Earth’s atmosphere, whose secondary particles reach the ground, eventually registered by ground-based detectors, specifically neutron monitors. This particular class of events is known as ground-level enhancements (GLEs). Here we report recent achievements related to the physics of relativistic SEPs/GLEs, their observations, and the related terrestrial and space weather effects.
Extreme solar particle events (ESPE) are a special class of solar energetic particle (SEP) events characterized by huge SEP fluxes, orders of magnitude greater than ever observed directly. The first event of this class, dated back to 774 AD, was found by Miyake and coworkers in 2012 in cosmogenic radiocarbon records in tree rings and identified as an ESPE. Today, four ESPEs are independently found and confirmed in different isotopes, and there are several more event candidates registered in radiocarbon that are awaiting confirmation in other cosmogenic proxies. In this work, we report a new method of the ESPE fluence reconstruction which simultaneously accounts for different cosmogenic-isotope datasets. For evaluations of the spectral shape of ESPEs, we used the recent reconstruction of strong SEP events registered by neutron monitors (GLE events), where GLEs SEP fluences were fitted with the combination of power-laws with exponential cutoffs. For each GLE we calculated the expected production/deposition of cosmogenic isotopes and then found (if that was possible) the scaling factor, which allows us to simultaneously fit all the available cosmogenic proxies signals for each ESPE. After that, we described the fluence for each of ESPEs with scaled fluences of separated GLEs, that allowed us to account for different SEP spectral shapes and hardnesses. The method also accounts for different sources of uncertainties (including changes in the geomagnetic field, the solar activity and measurement accuracy). In comparison to GLE #5 (23/02/1956), which was the hardest and the strongest directly registered GLE, ESPE events have a 30—70 times greater fluence making them strong manifestations of the solar activity.
The Baikal-GVD is a neutrino telescope under deployment situated in Lake Baikal - the deepest freshwater lake in the world. It is composed of independent operational units called clusters. In 2022, 10 clusters are data taking. The main goal of the Baikal-GVD neutrino telescope is the detection of astrophysical neutrinos.
In charged current interaction of tau neutrino the resulting tau lepton might decay into electron or hadrons. As a consequence a double cascade signature is created. The identification of high-energy tau neutrinos is considered to be a promising method for astrophysical neutrino detection.
In this poster, a technique for the reconstruction of double cascades in the Baikal-GVD will be described. The first flux estimations of tau neutrino double cascade events as well as the expected background rates will be presented.
A new paradigm of multisensory observations joined multiband measurements of the radiation coming from celestial objects to develop and confirm models of the origin of high-energy cosmic rays. The integral parameters of the cosmic ray flux, such as energy spectra and mass composition, mostly measured in the last century also bring useful information on the CR origination. Especially useful was an approach to disentangle the cosmic ray flux and obtain separately energy spectra of different mass groups by applying AI methods, first introduced in [1], and then realized for the MAKET-Ani [2] and KASCADE experiments [3].
The MAKET-ANI surface array operated on Aragats Mt. in Armenia in from 1997 to 2004 turned out to be very well suited for the energy and composition measurements at the “knee” of the cosmic ray spectrum. The problem of event-by-event classification of EAS has been solved by using Bayesian and neural network techniques [4]. The evidence from MAKET-ANI data can be summarized as follows:
The estimated energy spectrum of the light mass group of nuclei shows a sharp knee: ∆γ ~0.9, compared to ~0.3 for the all-particle energy spectra.
The energy spectrum of the heavy mass group of cosmic rays shows no break in the energy interval of 1015 2x1016 eV. In the new era of EAS studies by HAWK and LHAASO experiments aimed to detect point sources of gamma radiation and energy spectra of species of primary cosmic rays, it is interesting to present and analyze the full pattern of available energy spectra in the energy range from 1013 1017 eV, from already finished and just starting EAS experiments.
References
[1] A.Chilingarian, G.Zazyan, On the possibility of investigation of the mass composition and energy spectra of primary cosmic ray (PCR) in the energy range from 1015 to 1017 eV using EAS data, Nuovo Cimento C, 14 C, 555-568, 1991. [2] [2]A.Chilingarian , G. Gharagyozyan , G. Hovsepyan , S. Ghazaryan , L. Melkumyan,
and A. Vardanyan , Light and Heavy Cosmic Ray Mass Group Energy Spectra as Measured by the MAKET-ANI Detector, Astrophysical Journal, 603:L29-L32, 2004
[3] T.Antoni, WD Apel, AF Badea, et al., KASCADE measurements of energy spectra for elemental groups of cosmic rays: Results and open problems, Astroparticle physics, 24, 1-25, 2005.
[4]A.Chilingarian , G. Gharagyozyan , G. Hovsepyan , et al., Study of extensive air showers and primary energy spectra by MAKET-ANI detector on Mount Aragats, Astroparticle Physics, 28, 58–71, 2007
Measurements of the natural radiation background, specifically in the upper troposphere and low stratosphere, are important in order to compare and eventually inter-calibrate different experimental set-ups, as well as to provide a reliable basis for improving the existing models related to the environmental radiation in the Earth's atmosphere. Here, we report results from a new zero-pressure stratospheric balloon flight in the frame of the HEMERA-2 mission, obtained by measurements performed with a small portable device, (MDU)-1 Liulin. We derived the altitude profile of the atmospheric radiation in the Arctic region, namely in between estrange Kiruna, Sweden and Rovaniemi, Finland. The preliminary analysis shows a good agreement between the measurements and Oulu models for atmospheric ionization and exposure to radiation.
This investigation is based on a new model CORSIMA (COsmic Ray Spectra and Intensity in Middle Atmosphere). Numerical simulations of Galactic Cosmic Ray (GCR) spectra and intensity for the middle atmosphere and lower altitudes of the ionosphere (30-100 km) are presented. These altitudes are above the Regener-Pfotzer maximum.
The full GCR composition (protons p, alpha particles α, and heavier nuclei groups: light L, medium M, heavy H, very heavy VH) is used.
Analytical expressions for the energy interval contributions are provided. An approximation of the ionization function on six energy intervals is used and the charge decrease interval for electron capture is studied.
The development of this research is important for a better understanding of the processes and mechanisms of space weather. GCR has an impact on the ionization and electrical parameters in the atmosphere and also on the chemical processes (ozone formation and depletion in the stratosphere) in it.
Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported discovery of 12 ultrahigh-energy (UHE; ε > 100 TeV) gamma-ray sources located in the Galactic plane. We have used the multiwavelength radiation from these sources by considering a PWN origin, where the emission is powered by time-dependent spin-down luminosity of the associated pulsars. In this time-dependent leptonic emission
model, the electron population is calculated at different times under the radiative (synchrotron and inverse-Compton) and adiabatic cooling. The escape of particles from these PWN has been studied and their effects on the model parameters is estimated.
We present an updated analysis of the mass composition of cosmic rays in the $10^{17}$ to $10^{18}$ eV energy range. It is based on radio measurements of the depth of shower maximum $X_{\rm max}$, done with the LOFAR telescope.
We review the improvements to the reconstruction setup based on Corsika/CoREAS simulations, as well as the selection method to obtain a minimally biased $X_{\rm max}$-dataset. Systematic uncertainties on Xmax have been lowered to an estimated 7 to 9 g/cm$^2$, at a resolution of 20 g/cm$^2$ per shower.
Results include estimates of the mean and standard deviation of the $X_{\rm max}$-distribution. A statistical analysis at distribution level has been done as well, using a four-component model of light to heavy nuclei.
It confirms our previous results showing a significant low-mass fraction in this energy range.
We discuss consistency with existing results on $X_{\rm max}$ and mass composition.
The Auger Engineering Radio Array (AERA), as part of the Pierre Auger Observatory, is an array of $153$ radio antennas spanning an area of $17$ km$^2$, currently the largest of its kind, that probes the nature of ultra-high-energy cosmic rays at energies around the transition from Galactic to extra-galactic origin. It measures the MHz radio emission of extensive air showers produced by cosmic rays hitting our atmosphere. In this talk, we will present the recent work by AERA, such as the measurement of the muon content of inclined air showers and the stability of the measured radio signal over almost a decade, as measured with the Galactic radio background. In particular, we highlight the measurements of the depths of the shower maxima $X_\mathrm{max}$, which we use to make inferences about the mass composition of cosmic rays. We reconstruct $X_\mathrm{max}$ with a likelihood analysis, by comparing the measured radio footprint on the ground to an ensemble of footprints from Monte-Carlo CORSIKA/CoREAS air shower simulations. We compare our $X_\mathrm{max}$ reconstruction with fluorescence $X_\mathrm{max}$ measurements on a per-event basis, a setup unique to the Pierre Auger Observatory, and show the methods to be fully compatible. Furthermore, we extensively validate our reconstruction by identifying and correcting for systematic uncertainties. We determine the resolution of our method as a function of energy and reach a precision better than $15$ g$\,$cm$^{-2}$ at the highest energies. With a bias-free set of around $600$ showers, we find a light to light-mixed composition at energies between $10^{17.5}$ to $10^{18.8}$ eV, also in agreement with the Auger fluorescence measurements.
IceCube Neutrino Observatory is a multi-component detector embedded deep within the South-Pole Antarctic ice. The integrated operation of IceCube with its surface array, IceTop, makes it a unique three-dimensional detector. This facilitates detailed cosmic-ray analysis in the transition region from Galactic to extragalactic sources. This work will present the recent results from improvements made to estimate energy spectrum and composition with cosmic-ray measurements from IceCube and IceTop. For the energy and mass estimation, the work will detail a unique Graph Neural Networks-based approach that benefits from using signal-footprint information and reconstructed cosmic-ray air shower parameters. The implementation improves upon the standard likelihood-based analysis and reduces the computing time and cost for performing such analysis. In addition to this, the work will also introduce new composition-sensitive parameters for improving cosmic-ray composition estimation, potentially improving our understanding of high-energy muon deposits in cosmic-ray air-showers.
The energy spectrum and mass composition of ultra-high energy cosmic rays inferred at the Pierre Auger Observatory are used to derive a benchmark scenario for the emission mechanisms at play in extragalactic accelerators as well as for their energetics and for the abundances of elements in their environments. Assuming a distribution of sources following the density of stellar mass, the gradual increase of the cosmic ray mass number observed on Earth from ${\simeq}\: 2$\:EeV up to the highest energies is shown to call for nuclei accelerated up to an energy proportional to their electric charge and emitted with a hard spectral index. In addition, the inferred flux of protons down to ${\simeq}\: 0.6$\:EeV is shown to require for this population a spectral index significantly softer than that of heavier nuclei. This is consistent with in-source interactions that shape the energy production rate of injected charged nuclei differently from that of the secondary neutrons escaping from the confinement zone. Together with the inferred abundances of nuclei, these results provide constraints on the radiation levels in the source environments. Within this scenario, an additional component that falls off steeply with increasing energy up to the ankle feature is necessary to make up the all-particle flux in the sub-ankle energy range.
Mini-EUSO is a telescope launched on board the International Space Station in 2019 and currently located in the Russian section of the station and viewing our planet from a nadir-facing UV-transparent window in the Zvezda module. The instrument is based on an optical system employing two Fresnel lenses and a focal surface composed of 36 Multi-Anode Photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity and an overall field of view of 44$^\circ$. Mini-EUSO also contains two ancillary cameras to complement measurements in the near infrared and visible ranges. Main scientific objectives of the mission are the search for nuclearites and Strange Quark Matter, the study of atmospheric phenomena such as Transient Luminous Events, meteors and meteoroids, the observation of sea bioluminescence. Mini-EUSO can map the night-time Earth in the near UV range (predominantly between 290 – 430 nm), with a spatial resolution of about 6.3 km and different temporal resolutions of 2.5 $\mu$s, 320 $\mu$s and 41 ms. Mini-EUSO observations are extremely important to better assess the potential of a space-based detector of Ultra-High Energy Cosmic Rays (UHECRs) such as K-EUSO and POEMMA. In this contribution we describe the detector and present the various phenomena observed in the first two years of operation and place them in the context of UHECR observations from space.
We present the new insight into our ongoing mass composition analysis based on KASCADE archive data using deep neural networks. The archive consists of ~300M air shower events detected by a 16x16 array of scintillating detectors and spans from 1996 to 2013. Our goal is to reconstruct the initial particle from that data accurately. We introduced five mass groups; thus, the reconstruction process could be interpreted as a classification task.
Aside from decision trees, we have engineered multiple promising neural network architectures - self-attention perceptrons, visual transformers, and convolutional neural networks. These models are being trained on CORSIKA simulations; we thoroughly examined the behavior of our models on different hadronic simulations and performed multiple sanity checks. We also check the credibility of our models with a small "unblinded" part of real KASCADE data.
Young massive stellar clusters are increasingly discussed as major contributors to the flux of Galactic cosmic rays. Westerlund 1, being the most massive young stellar cluster in the Milky Way, is a prime target to study in this regard. We present results from deep observations of the region around Westerlund 1 in very-high-energy gamma rays with the H.E.S.S. array of Cherenkov telescopes. We observe a large-scale (~2° diameter) emission region with a shell-like structure, extending much beyond the stellar cluster itself. No indications for a variation of the source morphology with energy could be found, the combined energy spectrum extends to several tens of TeV. Apart from Westerlund 1, no other potential counterparts were found that can be responsible for the bulk of the gamma-ray emission. We discuss various different explanations for the origin of the gamma-ray emission, considering both cosmic-ray acceleration at shock fronts within the cluster as well as scenarios related to the powerful combined cluster wind.
Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA) is an air shower array experiment aiming to observe cosmic rays and gamma-rays in the southern hemisphere. The array will cover an 83,000$\rm{m^{2}}$ surface area with 400 scintillating plastic counters at the plateau (4,740m a.s.l.) of the Chacaltaya mountain in Bolivia. Underground muon detectors covering 3,700 m2 in the area allow a clear identification of muon components in air showers, enabling us to discriminate between hadronic and electromagnetic showers. Construction of half density ALPACA, which covers the same area but with 200 counters, is scheduled for 2023.
In the southern sky, the Galactic Center is a possible candidate for PeV particle accelerators, PeVatrons. Observations of sub-PeV gamma rays are essential to test the existence of PeVatrons, but so far, the energy spectrum is measured up to a few tens of TeV. The half density ALPACA is designed to have a sufficient sensitivity to test the gamma-ray emission from the Galactic Center in this energy range.
In this contribution, the performance of the half density ALPACA to a hypothetical gamma-ray source with the same trajectory and energy spectrum as the Galactic Center is reported. In addition to the effective area, the angular and energy resolutions in the gamma-ray observations and the differential flux sensitivity after the cosmic-ray background rejection are presented. If the spectrum is extended up to the 100 TeV region from the TeV measurements keeping the power-law function, more than 5 sigma detection at 100 TeV is expected during two-year observation.
The radio-quiet gamma-ray pulsar PSR J2021+4026, in the Gamma Cygni supernova remnant, is one of the brightest Fermi-LAT pulsars. It first drew attentions in October 2011, when it underwent an abrupt drop in its gamma-ray flux, with a simultaneous increase in its spin-down rate. This mode change was followed by a smooth recovery phase around December 2014, then by a similar mode change in February 2018. Being the only variable isolated gamma-ray pulsar observed so far, PSR J2021+4026 has been studied during the whole duration of the Fermi-LAT mission and is currently being monitored. We report an updated LAT analysis focusing on the most recent variability event, which occurred in May 2020. In order to characterize the variability of the pulsar, we studied the variations in spectrum, timing and pulse profile in details. We discuss the results using the most recent pulsar models and linking the observed variations to changes in the configuration of the magnetosphere. Monitoring activities on this unique pulsar will help us understand the poorly known mechanisms of variability in gamma-ray emitting neutron stars.
MAGIC is a system of two Imaging Atmospheric Cherenkov telescopes, in operation since 2009 at the Observatorio del Roque de los Muchachos, in La Palma (Canary Islands, Spain). MAGIC is sensitive to photons in the energy band between few tens of GeV and few tens of TeV: the so-called very-high-energy gamma rays. In this talk, I present a selection of recent scientific highlights involving the MAGIC telescopes in a multi-wavelength and multi-messenger context. I will cover, among others: the discovery of the first gamma-ray burst at very high energies and how we have used the measured signal to look for signatures of the quantum nature of spacetime; the evidence for proton acceleration obtained from the detection at very high energies of the nova RS Ophiuchi in 2021; the first firm association of a neutrino event with a gamma-ray blazar; and our results from dark matter searches using a combination of dwarf spheroidal galaxies and other targets.
HESS J1843-033 is an unidentified TeV gamma-ray source reported by H.E.S.S. Galactic Plane Survey (Hoppe, ICRC2008, H.E.S.S. Collaboration, A&A 612, A1, 2018). In the adjacent region, HAWC and LHAASO also discovered high-energy gamma-ray sources (Abeysekara et al., PRL 124, 021102, 2020; Cao et al., Nature 594, 33, 2021), but their origins remain unclear, and the relation of these gamma-ray emissions is not discussed yet. In this talk, we present the detailed results of the observation of gamma rays in the multi-ten TeV to sub-PeV energy range from the HESS J1843-033 region with the Tibet air-shower array and the underground muon-detector array, including the discussion about the origin of the gamma-ray emission and its association with some nearby celestial sources.
The investigation of the energy spectrum and the mass composition of cosmic rays in the 1 TeV - 1 PeV energy range is an important topic in astroparticle physics, as it can provide clues to understand the origin, acceleration mechanism and propagation of high-energy cosmic rays in our galaxy, as well as to find out the link between the TeV and the PeV cosmic-ray radiation. At HAWC, extensive air showers from TeV cosmic rays are recorded at a rate of 25 kHz using a 22000 $m^2$ array of 300 water Cherenkov detectors, each of them instrumented with 4 photomultipliers. The instrument measures different shower observables such as the arrival direction, the core position at ground, the lateral age and distribution and the primary energy, which allow to perform a variety of studies on the energy spectrum, composition and arrival direction of TeV cosmic rays. In this work, we have estimated the energy spectrum of H+He nuclei of cosmic rays between 6 TeV and 158 TeV. The spectrum was obtained by applying a Bayesian unfolding method on a subsample of air-shower data, which has a purity of 82% of H+He induced events. The spectrum was corrected for the contamination of heavy cosmic-ray nuclei. The subsample was extracted from the measured data by applying an energy dependent cut on the shower age of the events that was derived from Monte Carlo simulations with QGSJET-II-04. We found the existence of a cut in the spectrum of H+He cosmic ray nuclei close to 24 TeV with a statistical significance of 4.1$\sigma$.
The HAWC observatory is an air shower detector well suited for the research of cosmic rays in the energy interval between 10 TeV to 1 PeV , which is very interesting because in this range the data from space-borne detectors and extensive air shower experiments overlap. This fact opens the possibility to perform cross checks between direct and indirect cosmic ray detector techniques and to study the systematic errors that affect each detection technique. In this work, we present an update of the all-particle energy spectrum of cosmic rays between 10 TeV and 1 PeV that was obtained from an unfolding analysis applied on three years of HAWC's data. The shower events were collected from January, 2018 to December, 2020. The results show the presence of a knee-like structure around tens of TeV, which was previously reported by the HAWC collaboration in 2017. For the calibration and the energy estimation, we employed the high-energy hadronic interaction model QGSJET-II-04.
Lorentz Invariance Violation (LIV) can be studied in various sectors of
high-energy particle physics. Since its effects are predicted to
increase with energy, ultra-high energy cosmic rays and gamma rays are
powerful probes for testing different LIV models. In this work, the
unprecedented statistics and data quality collected by the Pierre Auger
Observatory in the EeV range are used to explore LIV scenarios. A
phenomenological approach of LIV is considered by introducing a generic
modification of the energy dispersion relation of the particles, which
is compatible with the Coleman and Glashow approach. This may affect the
kinematics of the interactions in the extragalactic propagation and in
the shower development in the atmosphere. To test this, a fit of the
spectrum and composition observables considering LIV in the propagation
of nuclei is used as a tool to show the sensitivity of the data to LIV.
Also, under certain LIV assumptions for the GZK photons propagation, it
is possible to constrain the violation using the photon flux limits. For
the electromagnetic sector, while no constraints can be obtained in the
absence of protons beyond $10^{19}$ eV, we obtain $\delta_{\gamma,0} > -10^{-21}$,
$\delta_{\gamma,1} > -10^{-40} \ \mathrm{eV}^{-1}$ and $\delta_{\gamma,2} > -10^{-58} \
\mathrm{eV}^{-2}$ in the case of a subdominant proton component up to
$10^{20}$ eV. For the hadronic sector, we study the best description of
the data as a function of LIV coefficients and we derive constraints in
the hadronic sector such as $\delta_{\mathrm{had},0} < 10^{-19}$, $\delta_{\mathrm{had},1} < 10^{-38} \
\mathrm{eV}^{-1}$ and $\delta_{\mathrm{had}} < 10^{-57} \ \mathrm{eV}^{-2}$ at
5$\sigma$ CL.
The Pierre Auger Observatory is the largest astroparticle experiment in operation. Complementing to the measurements of the charged ultra-high energy (UHE) cosmic rays, it has a very good sensitivity to the detection of photons and neutrinos. Since the UHE photon and neutrino fluxes are correlated to the acceleration mechanisms of charged particles, searches for these neutral particles enhance the multi-messenger understanding of UHE cosmic-ray sources and of transient astrophysical phenomena. In addition, searches for diffuse fluxes may bring information about exotic scenarios such as the decay of hypothetical super-heavy dark matter in the Galactic halo. The search for photon and neutrino primaries with Auger data is driven by the measurements of extensive air-showers with hexagonal grids with more than $1600$ water-Cherenkov detectors covering $3000\,$km$^2$. This surface array is overlooked by $27$ fluorescence telescopes. In this contribution, we present an overview of the current UHE photon and neutrino searches at the Observatory and discuss the most recent results. We report on stringent limits to the UHE photon and neutrino diffuse and point-like fluxes above $10^{17}\,$eV, which lead to strong constraints on theoretical models describing the nature of dark matter candidates and the sources of the most energetic particles in the Universe.
To find and understand the sources of ultra-high-energy cosmic rays necessitates to measure the properties of these particles with high precision. One of the objectives of the upgrade of the Pierre Auger Observatory is to increase in particular the mass sensitivity of the observatory and to identify the particle types with unprecedented precision. Part of this upgrade is the Radio Detector (RD): radio antennas, sensitive in the frequency band from 30 to 80 MHz will be added to each Surface Detector station of the observatory, thus, forming a 3000 km$^2$ radio detector with almost 1700 detector stations. Each station is equipped with two loop antennas, one oriented parallel to the geomagnetic field and the other perpendicular to it. We present the expected performance of the detector systems, derived from detailed end-to-end simulations. An engineering array with ten stations has been installed in fall 2019 in order to verify the calibration and air shower reconstruction procedures. We will present the status of the activities and give an outlook on the installation and commissioning process for the world’s largest radio array for cosmic rays.
In 2021 the first three stations of the Radio Neutrino Observatory Greenland (RNO-G) have been deployed, consisting of in-ice strings of antennas down to 100 meters and antennas just below the surface. Apart from measuring ultra high energy neutrinos, RNO-G will be able to detect cosmic rays with a total effective area of close to ~100km\textsuperscript{2} above 0.1 EeV. Air showers are an important verification measurement and source for in-situ calibration of the detector. Prospects for in-ice signal of air shower are developing further: Simulations suggest energy dense cores which propagate though the ice and are visible to deep antennas. In addition, stochastic energy losses from high energy muons in an air shower penetrating the ice may mimic the interaction of a neutrino. An efficient surface trigger will provide a veto mechanism for both types of events. The collected data of shallow and deep antennas can be used to verify simulations for in ice development of air showers.
We present first steps of the search for ultra-high-energy (> PeV) gamma rays based on archival data acquired by the KASCADE experiment.
This one operated from 1996 to 2013 and the collected statistics is comparable with those of modern ovservatories. The data is provided by the KASCADE Cosmic ray Data Center (KCDC) and public accessible.
Since the signatures left by gamma rays and protons background are similar, the main aim of the research is to distinguish them with machine learning methods.
For that, we present a primary particle type classifiers (gamma or not) trained on the basis of the simulation data of the KASCADE detector. We use and compare results of various deep learning methods as a graph neural network, self-attention network, compact convolutional transformer.
Surface detector arrays sample the distribution of particles from extensive air showers arriving at the ground. For a shower arriving from the zenith and for a flat array, this distribution is effectively radially symmetric. For inclined showers, however, detectors sample the shower at different stages in its development. Together with related attenuative and geometric effects, this results in radial asymmetries which differ between the various components of air showers. Left unaccounted for, these asymmetries may induce biases in the reconstructed position of a shower's core and in the reconstructed arrival direction of its primary. We present a parameterized model of these asymmetries as they manifest in the signals of two types of detectors commonly used to measure extensive air showers, namely scintillator and water-Cherenkov detectors. Additionally, we demonstrate the impact of taking these asymmetries into account during reconstruction. The results presented here are based on air showers simulated for proton and iron primaries with energies at and above $10^{18.5}\,$eV and subsequent simulations of detector responses.
A ground-level enhancement (GLE) is defined as a strong event with high-energy solar energetic particles (SEPs) detected by the network of ground-based neutron monitors. Until now, 73 GLEs have been registered. In this work, we report a new reconstruction of the event-integrated spectra (fluences) of SEPs during 59 moderate and strong GLE events detected by NM network and satellite experiments. The reconstructions of SEP fluences are based on the “bow-tie” method employing the latest advances in NM data analysis (time-dependent GCR background and the use of the altitude-dependent NM yield function directly verified with the AMS-02 experiment data) and a detailed study of different uncertainties. As a result of this work, we obtained fluences of SEPs in the energy range from 30 MeV to a few GeV for GLE events since 1956, which were fitted with the modified Band-function (a double power-law function with two exponential cutoffs). An easy-to-use presentation of SEP fluences in the form of an analytical expression makes a solid basis for new studies in various fields, such as the influence of SEPs on the atmosphere and a statistical study of extreme solar activity.
The precision measurement of daily proton fluxes with AMS during ten years of operation in the rigidity interval from 1 to 100 GV is presented. The proton fluxes exhibit variations on multiple time scales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ~10 GV and ~20 GV respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.
After more than a century of discovering cosmic rays, a comprehensive description of their origin, propagation, and composition still eludes us. One of the difficulties is that these particles interact with magnetic fields; therefore, their directional information is distorted as they travel. In addition, as cosmic rays (CRs) propagate in the Galaxy, they can be affected by magnetic structures that temporarily trap them and cause their trajectories to display chaotic behavior, therefore modifying the simple diffusion scenario.
Here, we examine the effects of chaos and trapping on the TeV CR anisotropy. Concretely, we apply this method to study the behavior of CRs in the heliosphere since these heliospheric effects can be remarkably significant for this anisotropy. Specifically, how the distinct heliospheric structures can affect chaos levels. We model the heliosphere as a coherent magnetic structure given by a static magnetic bottle and the presence of temporal magnetic perturbations. This configuration is used to describe the draping of the local interstellar magnetic field lines around the heliosphere and the effects of magnetic field reversals induced by the solar cycles.
In this work, we explore the possibility that particle trajectories may develop chaotic behavior while traversing and being temporarily trapped in this heliospheric-inspired toy model and the potential consequences that it can have on the cosmic ray arrival distribution. It was found that the level of chaos in a trajectory is linked to the time the particles remain trapped in the system. This relation is described by a power-law that could prove to be inherently characteristic of the system. Also, the arrival distribution maps show areas where the different chaotic behaviors are present, which can constitute a source of time-variability in the CR maps and can prove critical in understanding the anisotropy on Earth.
The detailed measurement of the daily electron fluxes from May 20, 2011 to October 29, 2019 with the Alpha Magnetic Spectrometer on the International Space Station, is presented. Time variation of the fluxes on different time scales associated with the solar activity over half solar cycle 24 is shown. In addition, the comparison between the time variation of daily electron, positron and proton fluxes will be presented. The simultaneous precision measurements of elementary particles with different charge and mass reveal unexpected phenomena of the cosmic rays propagation in the heliosphere.
The launch of the satellite-borne PAMELA instrument on the 15th June 2006 opened a new era of high-precision studies of cosmic rays. Thanks to its low detection energy threshold and its long operativity, PAMELA was able to accurately measure the fluxes of several cosmic-ray species over a large energy range and study their time variations below a few tens of GeVs. In this presentation we will review PAMELA results on the time-dependent proton, helium and electron fluxes measured between a few tens of MeV/n and few tens of GeV/n from 2006 to 2014. Moreover, preliminary results of yearly energy spectra of deuterons, helium-3 and helium-4 nuclei below 1 GeV/n will be discussed. These measurements covered a time including the minimum phase of the 23rd solar cycle and the 24th solar maximum including the polarity reversal of the solar magnetic field. The PAMELA measurements have allowed to significantly improve the understanding of the charged-particle propagation through the Heliosphere, the charge-sign effect due to the drift motions of these particles and to calibrate state-of-the-art models of cosmic-ray transport in the Heliosphere.
The appropriate knowledge and forecasting of cosmic ion radiation experienced by spacecrafts at Earth location and by interplanetary probes during their transfer orbit is a piece of relevant information, especially for what concerns the estimation of the radiation hazard in electronic devices. The HelMod Model evaluates the solar modulation effect on local interstellar spectra of galactic cosmic rays (GCRs) by using a Monte Carlo approach to solve the Parker transport equation. The model was validated by means of comparison with experimental GCR spectra observed during high and low solar activity periods, in the inner and outer heliosphere, at the Earth's location, and outside the ecliptic plane. In this work, we present how the model can be used to assess the GCR contribution to the space radiation environment.
Thermal electrons cannot directly participate in the process of diffusive acceleration at electron-ion shocks because their Larmor radii are smaller than the shock transition width: this is the well-known electron injection problem of diffusive shock acceleration. Instead, an efficient pre-acceleration process must exist that scatters electrons off of electromagnetic fluctuations on scales much shorter than the ion gyro radius. The recently found intermediate-scale instability provides a natural way to produce such fluctuations in parallel shocks. The instability drives comoving (with the upstream plasma) ion-cyclotron waves at the shock front and only operates when the drift speed is smaller than half of the electron Alfvén speed. Here, we perform particle-in-cell simulations with the SHARP code to study the impact of this instability on electron acceleration at parallel non-relativistic, electron-ion shocks. To this end, we compare a shock simulation in which the intermediate-scale instability is expected to grow to simulations where it is suppressed. In particular, the simulation with an Alfvénic Mach number large enough to quench the intermediate instability shows a great reduction (by two orders of magnitude) of the electron acceleration efficiency. Moreover, the simulation with a reduced ion-to-electron mass ratio (where the intermediate instability is also suppressed) not only artificially precludes electron acceleration but also results in erroneous electron and ion heating in the downstream and shock transition regions. This finding opens up a promising route for a plasma physical understanding of diffusive shock acceleration of electrons, which necessarily requires realistic mass ratios in simulations of collisionless electron-ion shocks.
The flux of solar energetic particles (SEPs) varies at different time scales, from minutes to the 11-year solar cycle, forming an important highly variable radiation factor near Earth. However, measurements of the SEP flux are subject to large uncertainties as assessed by different methods and from different instruments. Here we report the results of a revision of annual integral SEP fluences derived from in-situ space-borne measurements since 1984 in five energy ranges, viz. above 10, 30, 60, 100 and 200 MeV, using observations performed onboard the GOES Earth-orbiting satellites. We performed a careful inter-calibration of the SEP fluxes to obtain a uniform dataset. This includes careful subtraction of the galactic cosmic ray background and precise calculation of annual SEP fluences. It appears that SEP fluences were significantly weaker, by a factor of 5–8, during the recent solar cycle 24 than during previous cycles 22 and 23, implying that the SEP fluence is affected by the level of solar activity. The occurrence probability density function of SEP annual fluences was evaluated for the five energy ranges. In particular, it was shown that the complementary cumulative distribution function is nearly perfectly fitted by the Weibull distribution allowing for a statistical extrapolation of the annual fluences to a centennial time scale.
Multi-messenger astrophysics has emerged as a rapidly growing field of research in the last decade, providing unique new insights into the properties of high-energy astrophysical sources. Such insights have been made possible by the complementary information carried by photons, cosmic rays, neutrinos, and gravitational waves about the astrophysical environments and processes in which they are produced. In this talk, I will review key recent results and the major follow-up questions that remain to be addressed with future observations.
We live in a golden age for astro-particle physics, with a significant number of experiments actively monitoring high-energy Universe. Many of these probes provide excellent tests of particle physics models of dark matter particles. In particular, experiments such as Fermi -LAT, AMS-02, Ice Cube, ... are significantly cutting into the parameter space of one of the most popular candidates, the WIMPs. In this talk I will describe some of the strategies and methods used to search for dark matter with astrophysical data. Special attention will be given to the latest indications of an unaccounted gamma-ray excess at few GeV in the Fermi-LAT data in the region around the Galactic Centre, which steered lots of attention as it was shown to be consistent with putative signals of WIMP dark matter particles and complementary constraints provided by other experiments. Finally I will discuss projections of the expected sensitivities with upcoming experiments and continued data taking with current ones.
In this talk we discuss recent observations and modelling endeavours of low-energy cosmic rays near Earth and in the inner heliosphere. We especially focus on observations that present a challenge to theoretical and numerical modelling studies. Topics include the record-setting galactic cosmic ray (GCR) levels observed during recent solar minima that were not accompanied by such high levels of anomalous cosmic ray (ACR) fluxes, the large gradient of ACRs in the very inner heliosphere, and the observations of Jovian electrons in this newly explored region close to the Sun where the isotropic Parker particle transport formalism may not be completely valid. These recent observations present interesting challenges to the long-established cosmic ray transport paradigm.
We present high statistics measurements of 15 cosmic ray nuclei, H to Si and Fe, based on 10 years of the AMS data.
The China Seismo-Electromagnetic Satellite (CSES-01) is a sophisticated space observatory to monitor the ionosphere and study its coupling with the magnetosphere and the lithosphere. Launched in February 2018, in the framework of a joint cooperation program between the Chinese and Italian Space Agencies, it includes payloads to measure the electric and the magnetic field, plasma, X rays and electrons and protons in a wide energy range. The High-Energy Particle Detector (HEPD-01) is a large field-of-view instrument, optimised to measure electrons (3-100 MeV), protons (30-300 MeV), and light nuclei (up to a few hundreds of MeV/nucleon). The HEPD has been designed and constructed by the Limadou collaboration, which also controls operations in flight and performs analysis and calibration to provide high-quality data to the scientific community. HEPD is maintained on a Sun-synchronous orbit and performs extremely well in particle identification and energy resolution, all features making it a sensitive probe for galactic, solar and trapped particles with energies between tens and hundreds of MeVs.
The launch of CSES-02, the second satellite of the constellation, is foreseen by mid-2023. Together with CSES-01, they will constitute the first multi-site cosmic-ray observatory in space. The second version of HEPD has been designed to improve the performance of HEPD-01 under all aspects, extending the energy range, increasing angular and energy resolution and refining upon particle identification, with good sensitivity also to gamma-ray transients. This progress is due two major technological innovations: the first use of Monolithic Active Pixel Sensors to track particles in space and a flexible trigger system prioritising and managing data acquisition from different signal patterns.
I will report on the results obtained with HEPD-01 in four years of data acquisition, with particular regard to the solar energetic particles and galactic cosmic rays measurements. Finally, I will describe the expected gain in sensitivity due to the combined operation of HEPD-01 and HEPD-02 from 2023.
Current challenges in astroparticle physics like the muon puzzle in air shower physics or the upcoming launch of next-generation neutrino and gamma observatories require modern tools for the simulation of particle propagation, both from a technical and a physical standpoint.
For those purposes, PROPOSAL is a simulation framework that provides 3D Monte Carlo simulations of charged leptons and high-energy photons.
PROPOSAL, which is usable in both C++ and Python, provides a high level of customizability, allowing the user to customize both the propagation environment and the underlying physical parametrizations, where up-to-date energy loss cross sections are available.
In this contribution, we present PROPOSAL as a framework, as well as current applications where PROPOSAL is used.
This includes the usage of PROPOSAL as an electromagnetic model for the shower simulation framework CORSIKA 8, as well as the usage of PROPOSAL for underground measurements of muon numbers, for example in the context of muography.
High-energy atmospheric muons are of special relevance to very large-volume neutrino telescopes as they constitute by far their major event yield. Understanding their characteristics at sea level can help to properly interpret the signal observed deep underwater. This work aims to investigate the flux as well as the charge ratio of atmospheric muons above 100 GeV at sea level. The calculations are carried out using the simulation program CORSIKA in combination with different up-to-date hadronic interaction models. The obtained results are compared with experimental data and with well-known analytical parametric models.
The SPHERE project studies primary cosmic rays by detection of the Cherenkov light of extensive air showers reflected from the snow covered surface of the earth. The SPHERE project is the first successful implementation of a new EAS detection method — detection of reflected Cherenkov light using an aerial-based detector — a method first proposed by A. Chudakov and first implemented by R. Antonov [1]. The SPHERE-2 experiment was designed for primary cosmic ray studies in the 10–1000 PeV energy range. The detector SPHERE-2 was lifted by a balloon to altitudes of up to 900 m above the snow covered surface of Lake Baikal, Russia. Measurements were performed in 2011--2013.
Here we present an overview of the SPHERE-2 [2] detector telemetry monitoring systems along with the analysis of the measurements conditions including atmosphere profile. The analysis of the detector state and environment atmosphere conditions monitoring provided various cross-checks of detector calibration, positioning, and performance.
Antonov, R., et al. Detection of reflected Cherenkov light from extensive air showers in the SPHERE experiment as a method of studying superhigh energy cosmic rays. Physics of Particles and Nuclei 2015, 46, 60–93. doi:10.1134/S1063779615010025
Antonov, R., et at. The SPHERE-2 detector for observation of extensive air showers in 1 PeV–1 EeV energy range. Astroparticle Physics 2020, 121, 102460. doi:10.1016/j.astropartphys.2020.102460
We develop a new algorithm for the production and propagation of cosmic ray (CR) secondary elements and hadronic gamma ray emission within the framework of Cosmic Ray Energy SPectrum (CRESP) module of Piernik MHD code (Ogrodnik et al ApJS 253, 18, 2021). CRESP is based on the piece-wise power-law (coarse-grained) method for self consistent and numerically efficient cosmic ray (CR) propagation in the magnetized ISM of galaxies. We shall demonstrate the application of the method in simulations of CR secondary nuclei and predicting their ratios to primary CRs in MHD simulations of galaxies such as the Milky Way.
Galactic outflows and extended non-thermal emission due to Comic Ray (CR) electrons were observed from many edge-on galaxies in radio range of electromagnetic radiation, allowing i.a. to estimate the strength and vertical structure of galactic magnetic field.
We construct a global model of NGC891, based on observational characteristics of this galaxy. We assume that on the large scales the dynamics of the magnetized ISM is driven by Cosmic Rays.
We apply the algorithm of energy-dependent propagation of CR electrons in ''Cosmic Ray Energy SPectrum'' (CRESP) module of PIERNIK MHD code to model CR propagation in this galaxy. The overall propagation of cosmic rays is described by energy-dependent diffusion-advection equation. We assume a piece-wise power-law, isotropic CR distribution function and apply a conservative, finite volume-type propagation of CR gas in momentum space.
The numerical model exhibits magnetic field amplification by CR-driven dynamo. We perform a parameter study of the system by varying the efficiency of conversion of supernova energy to CRs, the magnitude and momentum dependence of the CR electron diffusion coefficients. We take into account the advection, diffusion, adiabatic changes as well as synchrotron and inverse-Compton losses.
We find that the spectrum of synchrotron radiation, polarization maps and spectral index maps reproduce very well the observed structures of the real edge-on galaxy. Comparison of different models suggests higher conversion ratios of SN into CR energies and likely higher diffusion coefficients.
Supernova Remnants (SNRs) are considered as the primary sources of galactic cosmic
rays (CRs), where CRs are assumed to be accelerated by diffusive shock acceleration (DSA) mechanism, specifically at SNR shocks. In the core-collapse scenario, the SNR shocks expand inside the complex ambient environment as the core-collapse SNRs have massive progenitor stars ($> 8M_\odot$) and those stars generate wind-blown bubbles during their different evolutionary stages as a consequence of their mass-loss in the form of stellar wind. Additionally, as the evolution of massive stars depends on the Zero Age Main Sequence (ZAMS) mass, rotation, and metallicity the structures of created circumstellar medium are considerably different. Therefore, the CR acceleration and the radiation from the core-collapse SNRs should differ significantly not only from the SNR, evolving in the uniform environment but also from one another, depending on their progenitor stars.
We aim to observe the influence of the ambient medium of core-collapse SNRs on the
particle spectra and radiation as well as to probe the change in spectral shape if SNRs have progenitors with lower($>8M_{\odot}$ ), intermediate, and very high ZAMS mass.
We applied the hydrodynamic structures of wind-blown bubbles at the pre-supernova stage created by massive stars with $20M_{\odot}$, $35M_{\odot}$, and $60M_{\odot}$ ZAMS masses to form the ambient environment for supernova explosions. The evolution of those stars through notably different stages from Zero Age Main Sequence (ZAMS) to the pre-supernova stage results in the formation of structurally different wind bubbles, hence preferable to observe the spectral shape dependency on the mass of progenitor stars. Then, the transport equation for cosmic rays, hydrodynamic equations have been solved simultaneously in 1-D spherical symmetry.
We have obtained the modifications in particle spectra are significantly determined by the hydrodynamic structure of SNR ambient medium. The spectral shape depends considerably on the interplay of SNR shock interactions with different discontinuities inside the wind bubble and the temperature of the bubble. The $60M_{\odot}$ star ends life as a Wolf-Rayet star and creates a very hot bubble ($>10^8\,K$). As consequence, we have found softer particle spectra with spectral index close to 2.5. For comparison, $20M_{\odot}$ star becomes a Red-Supergiant at pre-supernova stage and hence the created bubble would not be hot enough to provide the spectral softness as for the SNR with $60M_{\odot}$ progenitor. Furthermore, the circumstellar magnetic field structure, as well as the considered particle diffusion coefficient in the simulation effectively influence the particle acceleration as well as emission morphology of SNRs.
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Recent theoretical and numerical studies incorporating cosmic rays (CRs) into global modelling of magnetized interstellar medium demonstrate that CRs can play an important role in the generation of large-scale galactic magnetic fields and, at the same time, in driving galactic winds. Cosmic-Ray-driven dynamos produce magnetic arms in galactic disks and large-scale helical magnetic fields in galactic halos.
A new element of our present model is the population of CR electrons injected in SN remnants together with CR protons. We use the recently developed Cosmic Ray Energy Spectrum - CRESP module of PIERNIK MHD code (Ogrodnik et al 2021) to study the propagation of spectrally resolved CR electrons, coupled with the MHD evolution of modelled galaxies. The CRESP module is designed for modelling energy-dependent transport, of Cosmic Ray (CR) electrons in galactic magnetic fields. The module solves the Fokker-Planck equation for CR electrons characterized by the piece-wise power-law distribution function, with synchrotron, inverse Compton and adiabatic cooling effects are taken into account together with diffusive and advective propagation of CR electrons on an Eulerian grid.
We use the dynamical models of spectral evolution of synchrotron emitting electrons to generate synchrotron emission maps at different radio frequencies together with maps of spectral index and Faraday rotation. We demonstrate that the inclusion of the spectral evolution of CR electron population, combined with MHD modelling of galaxies, opens new opportunities for observational diagnostics of ISM dynamics, CR propagation parameters and for verification of galactic magnetic field structures and amplification models.
The magnetorotational instability (MRI) is believed to generate the MHD turbulence necessary for efficient outward angular momentum transport in various black hole accretion disks. In low-luminosity accreting black holes, the density in the accreting plasma is so small that particle-particle Coulomb collisions occur very infrequently, making these disks effectively “collisionless”. These collisionless disks around black holes are ubiquitous at the center of nearby galaxies (these include the EHT targets M87 and Sgr A*, at the center of our own Milky Way). Under these conditions, it is believed that particles may develop a non-thermal population and get accelerated to high energies.
We present results of fully kinetic, particle-in-cell plasma simulations of the collisionless MRI, where non-thermal phenomena are included from first principles. Our simulations are local and stratified, which means that we use the local shearing box approximation and include the vertical structure of the disks. This means that our study simultaneously captures the evolutions of the disk midplane as well as the (more magnetized) disk corona. Our study concentrates on the MRI evolution for plasma temperatures relevant at tens of gravitational radii from the central black hole. We find that particle acceleration in our stratified simulations is, on average, significantly more efficient than in the case where disk stratification is not included.
Pulsars dominate the local cosmic-ray positron flux at high energies by producing electron-positron pairs from their spindown energy. While the AMS-02 experiment, that measures the cosmic-ray flux to great precision, shows that the positron flux is very smooth, simple simulations of pulsar models predict sharp spectral features. In this work, we add several mechanisms to model the local positron flux more realistically. Specifically, we implement a more realistic positron production mechanism of the pulsars, and take into account various effects on the energy losses of the positrons as they propagate through the Galaxy. Our models show that the sharp spectral features predicted by the simple models vanish, which is consistent with the observed smoothness of the local cosmic-ray positron flux. This re-opens the possibility that sharp spectral features in the cosmic-ray positron flux could provide strong evidence of dark matter annihilation.
Star-forming galaxies are known to have been abundant at redshifts above z~6, and recent observations have revealed examples of high redshift primordial galaxies with evolved stellar populations and complex star-formation histories (SFHs) spanning into the first 250 Myr after the Big Bang. In these systems, intense bursts of star-formation appear to be interspersed with sustained periods of strong quenching, however the processes underlying this evolutionary behaviour remain unclear. Unlike in later epochs, galaxies in the early Universe would co-evolve with their circumgalactic halo as a relatively isolated ecosystem. Although the intense star-formation bursts may be fuelled by gaseous inflows from the cosmic web, circumgalactic flows would connect to a galaxy’s internal environment, allowing for recycling of matter, energy and particles. Thus, the mechanisms that could bring about the downfall of star-formation in these early galaxies are presumably intrinsic, with feedback processes associated with intense bursts of star-formation likely to play an important role. In this talk, I will discuss how cosmic rays are likely to be an important agent to deliver this feedback, and show how they can account for the SFHs inferred from recent observations of these systems. Moreover, I will discuss how signatures of cosmic ray induced quenching may be accessible in young starbursts and possible lower-redshift isolated analogues.
Active Galactic Nuclei (AGNi) can launch and sustain powerful outflows of very high velocity and large opening angle.
Provided that the activity lasts long enough such outflows develop a bubble structure characterized by an inner wind shock and an outer forward shock.
During the time the forward shock expands in the surrounding medium, the inner wind shock quickly decelerates while remaining strong, thereby creating ideal conditions for stationary particle acceleration.
We model the diffusive shock acceleration process at the wind shock of such AGN-driven winds and we explore the multimessenger implications in terms of high energy photons and neutrinos.
Last decade the research in high-energy physics in the atmosphere (HEAP) was mostly concentrated on measuring the particle fluxes from the electrified atmosphere (thunderstorm ground enhancements, TGEs, and Terrestrial gamma flashes, TGFs) and revealing their origin. Afterward, in 2021 started the research of the atmospheric electric fields using particle fluxes traversing thunderstorms and registering on the earth’s surface with particle spectrometers. The new approach gives very interesting results, sometimes contradicting the common knowledge on the vertical profile of atmospheric electric field, however, supported by the exact methods of particle physics and well-established theories of the electromagnetic interactions.
First of all, it was confirming of a model of electron acceleration in the strong atmospheric electric fields [1]. Then using the largest TGEs obtained on Aragats and Lomnicky Stit we estimated the maximum achievable potential drop (voltage) on these summits to be consequently 300 and 500 MV [2,3]. Afterward, we use the modulation of the “muon beams” by strong atmospheric electric fields to investigate the disturbances of the atmospheric electric field [4]. Finally, profiting from the 24/7 operation of the Aragats Solar neutron spectrometer (ASNT), we develop a methodology for the remote monitoring of the vertical profile of electric field in thunderclouds [5]. Thus, the synergy of cosmic ray and atmospheric physics allows explaining all types of particle bursts within one framework, i.e., as consequences of extensive air showers.
References
1. A. Chilingarian, G. Hovsepyan, E. Svechnikova, and M. Zazyan, Electrical structure of the thundercloud and operation of the electron accelerator inside it, Astroparticle Physics 132 (2021) 102615 https://doi.org/10.1016/j.astropartphys.2021.102615.
2. A.Chilingarian, G. Hovsepyan, G.Karapetyan, and M.Zazyan, Stopping muon effect and estimation of intracloud electric field, Astroparticle Physics 124 (2021) 102505.
3. A.Chilingarian, T.Karapetyan, H.Hovsepyan, et. al., Maximum strength of the atmospheric electric field, PRD, 2021, 103, 043021 (2021).
4. Chilingarian, A., Hovsepyan, G., & Zazyan, M. (2021). Muon tomography of charged structures in the atmospheric electric field. Geophysical Research Letters, 48, e2021GL094594. https://doi.org/10.1029/2021GL094594
5. A.Chilingarian, G. Hovsepyan, and M. Zazyan, Measurement of TGE particle energy spectra: An insight in the cloud charge structure, Europhysics letters (2021), 134 (2021) 6901, https://doi.org/10.1209/0295- 5075/ac0dfa
This work represents the research related to the modeling of cosmic rays propagation through the Earth atmosphere and calculation of the specific yield function in form of ionization profiles at different depths (altitudes). The simulation have been performed with the Monte-Carlo based GEANT4 software development toolkit, which includes the cascade models, the neutron interaction databases, and the low-energy electromagnetic interaction database. To model the entire atmosphere from the sea level to the 100 km altitude the NRLMSISE-00 model is used. Both comparison with the previous studies and the verification with an experimental data are given. The results are given in form of the Earth atmosphere ionization yield function datasets. They are presented in the table form, which allows one to quantify the ionization induced by cosmic ray particles for given geographic coordinates, altitude, and the initial energy spectrum of the cosmic ray source. The relevance of this research is due to the global interest in assessing the impact of space weather both on the whole Earth's environment and on the individual objects located in it.
Cosmic gamma ray bursts(GRB) are high energetic photos resulting from astrophysical events within and beyond our galaxy. Their energy is deposited in the upper atmosphere by ionization of the constituent atoms and molecules. The resulting plasma affects the absorption and hence the propagation of radio waves in the VLF range which can be used to detect and analyze GRB. In this work we are investigating the response of a SID monitor to GRB by modeling the ionization by GBRs in the ionosphere and the effects on the radio wave propagation. Subsequently we discuss the potency of the SID monitor for detection and analysis of GRBs and the implications to space-weather monitoring and applications.
The detailed measurement of the positron fluxes from May 20, 2011 to October 29, 2019 with the Alpha Magnetic Spectrometer on the International Space Station, is presented. Time variation of the fluxes on different time scales associated with the solar activity over half solar cycle 24 is shown. The measured effect of charge sign dependent effects on particles with the same mass is discussed.
The Tibet air shower array is located at 4,300m above sea level, Tibet, China. It is an international joint project between China and Japan. The Tibet air shower array which observes high-energy cosmic rays above 3 TeV. The Sun casts a shadow in high-energy cosmic-ray intensity observed at the Earth and the depth and location of the shadow vary according to variations of the solar magnetic field. We find a clear solar cycle variation of the deficit intensity in the Sun shadow in anti-correlation with the solar activities. Our MC simulation of the Sun shadow based on the potential field model of the coronal magnetic field reproduces the observed variation of the deficit intensity successfully above 10 TeV. However, we find small systematic difference between the MC simulation and our observation around 3 TeV. As a source of the difference, we examine the influence of the coronal mass ejections on the Sun shadow. On the other hand, the north-south displacement of the Sun shadow center is related to the away-toward interplanetary magnetic field, which we also discuss in this presentation.
Very High Energy Cosmic Rays are believed to be accelerated in astrophysical jets. The formation of such jets requires spinning black holes. Therefore, the modeling of spinning black holes is a fundamental diagnostics for Cosmic Ray acceleration. However, detecting spinning black holes is still a difficult task. The detectability largely depends on high-quality data and very importantly on their sophisticated modeling. In this talk I will present an explanatory example for which the modelling plays a crucial role. Very specifically, the high-energy observations of Mrk 876 hint at a spinning supermassive black hole. Yet, the detectability is hindered by the degeneracy of the parameters, even though further statistical properties favor the spin scenario.
The cosmic-ray fluxes of electrons and positrons ($e^{\pm}$) are measured with high precision by the space-borne particle spectrometer AMS-02. To infer a precise interpretation of the production processes for $e^{\pm}$ in our Galaxy, it is necessary to have an accurate description of the secondary component, produced by the interaction of cosmic-ray proton and helium with the interstellar medium atoms.
We determine new analytical functions of the Lorentz invariant cross section for the production of $\pi^\pm$ and $K^\pm$ by fitting data from collider experiments. We also evaluate the invariant
cross sections for several other channels, involving for example hyperon decays, contributing at the few % level on the total cross section.
For all these particles, the relevant 2 and 3 body decay channels are implemented, with the polarized $\mu^\pm$ decay computed with next-to-leading order corrections.
The cross section for scattering of nuclei heavier than protons is modeled by fitting data on $p+C$ collisions.
The total differential cross section $d\sigma/dT_{e^\pm}(p+p\rightarrow e^\pm+X)$ is predicted from 10 MeV up to 10 TeV of $e^\pm$ energy with an uncertainty of about 5-7 % in the energies relevant for AMS-02 positron flux, thus dramatically reducing the precision of the theoretical model with respect to the state of the art.
Finally, we provide a prediction for the secondary Galactic $e^\pm$ source spectrum with an uncertainty of the same level.
As a service for the scientific community, we provide numerical tables and a script to calculate energy-differential cross sections.
Current measurements of cosmic-ray fluxes have reached unprecedented accuracy thanks to the new generation of experiments, and in particular the AMS-02 mission. At the same time, significant progress has been made in the propagation models of galactic cosmic rays. These models include several propagation parameters, which are usually inferred from the ratios of secondary to primary cosmic rays, and which depend on the cross sections describing the collisions among the various species of cosmic-ray nuclei with the interstellar medium (spallation cross sections).
The current spallation cross sections are based on set of parametrizations mixing (few) data points and simulation predictions for those channels with no measurements. In this talk, we present new sets of spallation cross sections of cosmic-ray interactions in the Galaxy, both inelastic and inclusive, computed with FLUKA simulation code that has been extensively tested against data. Furthermore, these cross sections have been implemented in the DRAGON2 code to characterize the spectra of CR nuclei up to Z=26 (Iron) and study the main propagation parameters predicted from the spectra of secondary CRs such as B, Be and Li. These results and their implications will be discussed in the talk.
The AMS-02 detector on board the International Space Station provides precise measurements of high-energy galactic cosmic rays (CRs) near Earth, while the Voyager mission measures CRs outside the solar system, beyond the effects of solar modulation. Observations of CRs by Voyager and AMS-02 provide valuable information on the propagation of CRs in the galaxy. Here we present a revision of various CR propagation models compared with recent direct CR measurements by Voyager and AMS-02. We explore the performance of different classes of models and investigate how the data inform their parameters governing CR propagation.
Cosmic-ray feedback is suspected to affect star formation in molecular clouds by providing pressure support comparable to the thermal and magnetic ones. Thanks to numerical simulations, this extra support is known to drive galactic winds and thicken the galactic disc. The feedback efficiency, however, depends on CR transport properties which locally vary with interstellar turbulence, gas ionisation, and magnetic field line tangling, so we need to find observational clues about actual CR propagation properties in the different interstellar phases.
As a first step toward searching for new observational diagnostics, we have simulated the evolution of a gas-rich dwarf galaxy ( $\sim 10^{11}$ M$_{\odot}$ in total mass) with the adaptive mesh refinement code RAMSES, with 9 pc resolution. These simulations include cosmic rays that are advected by the gas and that diffuse either isotropically or along the magnetic field with uniform diffusion coefficients ranging from $3\times 10^{27}$ to $10^{29}$ cm$^2$ s$^{-1}$, to bracket the value inferred for the Milky Way. The simulation models the multiphasic structure of the interstellar medium. Unlike in other simulations, we find that the global $\gamma$-ray luminosities and star-formation rates of the simulated galaxies compare well with the observed $\gamma$-ray-FIR relation for anisotropic $10^{27.5-29}$ cm$^2$ s$^{-1}$ diffusion and for isotropic diffusion slower than about $3 \times 10^{28}$cm$^2$ s$^{-1}$. Our results, therefore, do not confirm claims of very fast diffusion $10^{29-31}$ cm$^2$ s$^{-1}$ to match the Fermi LAT observations. We also observe positive feedback of CR rays on the amplification of the magnetic field in the inner halves of the galaxies, except for fast isotropic diffusion. Whereas the global mass in the different gas phases is marginally altered when changing CR transport, the magnetic amplification can suppress star formation by a factor of three to four.
The paths of cosmic rays are deflected upon passing through the Galactic magnetic field structure. The strength of the deflections that these cosmic rays undergo is dependent on the strength and structure of the Galactic magnetic field. Unfortunately, our knowledge of the Galactic magnetic field is very limited, especially when considering the fields present in the Galactic halo region. In this talk, I wish to motivate the importance of the Galactic halo magnetic fields not only from the point of view of radio observations but also for ultra high energy cosmic ray propagation.
The observations from eROSITA and FERMI-LAT show clear evidence of large extended structures out in the Galactic halo region, with a total energy of up to ~1e56 ergs seen in thermal X-rays. However, most of the widely used Galactic magnetic field models focus predominantly on the Galactic disc rather than the halo. In Ref.~[1] we motivate a toy magnetic field model for the Galactic halo. We use this model, in combination with an analytic expression for the non-thermal electron distribution, to generate synthetic polarised synchrotron maps and compare them with 30 GHz Planck data. We obtain constraints on the parameters of our model and utilise these constraints to create arrival direction maps for ultra high energy cosmic rays. We conclude that present uncertainties in the field strengths can have major consequences on the arrival directions of the cosmic rays and thereby the source localisation.
The expected level of correlations between the position in the sky of the sources of ultra-high-energy cosmic rays (UHECRs) and their actual arrival directions at Earth depends on the strength of the magnetic fields governing their propagation and the density of the sources. We investigate which combinations of magnetic-field setups and source densities can explain the recently observed correlations between star-forming galaxies and UHECR directions. We do this by scanning over the strength and coherence length of the extragalactic magnetic field (EGMF) and over the source density, for a fixed Galactic magnetic field (GMF) model and UHECR spectrum and composition assumptions that fit the measured data of the Pierre Auger Observatory (PAO). Under the assumption that UHECRs are predominantly produced by star-forming galaxies, we find that rather strong EGMFs ($B > 0.2 \ \rm nG$ for a coherence length of $1 \ \rm Mpc$ at the $5\sigma$ confidence level) between the UHECR sources and the Milky Way are necessary to explain the observed correlations. If UHECRs are predominantly produced in sources with an even larger source density than star-forming galaxies, weaker EGMFs are allowed. However, this would mean that UHECRs are accelerated in relatively regular galaxies, which is hard to motivate. Too strong EGMFs, on the other hand, are also disfavoured, leading to an overall upper limit of $B < 22 \ \rm nG$ for a coherence length of $1 \ \rm Mpc$ at the 90\% confidence level.
The γ-ray emission from stars is induced by the interaction of cosmic rays with stellar atmospheres and photon fields. This emission is expected to come in two components: a stellar disk emission, where γ-rays are mainly produced in atmospheric showers generated by hadronic cosmic rays, and an extended halo emission, where the high density of soft photons in the surroundings of stars create a suitable environment for γ-ray production via inverse Compton (IC) scattering by cosmic-ray electrons. Besides the Sun, no other disk or halo from single stars has ever been detected in γ-rays. However, by assuming a cosmic-ray spectrum similar to that observed on Earth, the predicted γ-ray emission of super-luminous stars, like e.g. Betelgeuse and Rigel, could be high enough to be detected by the Fermi Large Area Telescope (LAT) after its first decade of operations. In this work, we use 12 years of Fermi-LAT observations along with IC models to study 9 super-luminous nearby stars, both individually and via stacking analysis. Our results show no significant γ-ray emission, but allow us to restrict the stellar γ-ray fluxes to be on average <3.3×10−11 ph cm−2 s−1 at a 3σ confidence level, which translates to an average local density of electrons in the surroundings of our targets to be less than twice of that observed for the Solar System.
The Global Cosmic Rays Observatory is a proposal for a new large-scale observatory to measure the properties of ultra-high energy cosmic rays. To discuss this proposal the first workshop, gathering more than 200 scientists, was followed by a meeting in July 2022 when a more detailed science case and detector design have been discussed. Several questions paved the way of discussions: In ten years from now what do we expect to unveil on the origin of cosmic rays, their nature, energy, and arrival directions? If a next-generation ground based experiment is built, which are the main characteristics to improve upon the results expected from Pierre Auger Observatory and Telescope Array experiment? Based on these expectations and the science case, which is the energy range to be addressed by this new Observatory? We will present the scientific results that might be achievable with GCOS in different science and detector configurations scenarios.
The High Energy cosmic-Radiation Detection (HERD) facility is a future experiment that will be installed aboard the China’s Space Station around 2027. Using a single instrument, the experiment aims to perform high energy measurements relative to cosmic ray, gamma astronomy and indirect dark matter search. This is possible thanks to the innovative design based on a homogeneous, isotropic and 3D segmented calorimeter, surrounded by scintillating fiber trackers, anti-coincidence scintillators, silicon charge detectors, and a transition radiation detector. The HERD instrument is designed to feature a very large acceptance, of about one order of magnitude larger than previous experiments, thus allowing to extend the measurements by about one order of magnitude in energy. Fundamental progresses in our understanding of acceleration and propagation of cosmic rays will be achieved by measuring the flux of protons and helium up to a few PeV and nuclei above hundreds of TeV/nucleon. By exploring the electron flux in the multi-TeV region, it will be possible to search for the signature of dark matter and nearby astrophysical sources. Finally, thanks to the large field of view, the experiment will also monitor the gamma-ray sky from a few hundreds of MeV up to the TeV region. In this contribution, a review of the current status of the experiment will be presented, with particular regards to the estimated detector performances and the expected physics results.
The observation of PeV cosmic rays is essential to solving the question on the origin of cosmic rays, but because these are affected by magnetic fields, $\gamma$-rays at the sub-PeV scale emerge as a better tool to search for sources in our galaxy.
In $2019$ the Tibet AS$\gamma$ collaboration reported the detection of sub-PeV $\gamma$-rays coming from the Crab nebula using a novel technique with a hybrid Surface Array and underground muon detector to improve the discrimination against hadrons. Using this technique we will explore the $gamma$-ray sky in the Southern Hemisphere through a new experiment: the Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA).
The future detector to be installed near the Chacaltaya mountain at an altitude of $4740$ $\mathrm{m}$ will cover an area of $83000$ $\mathrm{m}^{2}$ with $400$ scintillation counters and $4$ underground muon detectors of $900$ $\mathrm{m}^{2}$. A prototype array called ALPAQUITA, having $1/4$ of the total area of the full ALPACA, is planned to start scientific observations in $2022$ and then expand to cover the full area of the array but with half density.
In this presentation, we will introduce the capabilities of the ALPACA experiment and the current status of ALPAQUITA, and plans to extend and improve the basic design. In this sense, we will include our efforts in developing a flexible DAQ system and further techniques to improve the $\gamma$/CR separation.
Over the last couple of years, particle detectors at high elevation sites provided a fresh look at the gamma-ray sky. Observatories, like HAWC, and more recently LHAASO, have significantly increased the number of TeV observed gamma-ray sources and opened up a new energy regime in astronomy. Several astrophysical objects are now confirmed to emit significantly above 100 TeV photon energy, marking the beginning of ultra-high-energy gamma-ray astronomy. The recent successes of this technique have all been obtained in the Northern sky, while some of the most prominent astrophysical targets are only observable from the South. This motivated the development of the Southern Wide-field Gamma-ray Observatory. In this contribution, I will provide an overview of the goals and current status of this project.
Context. The Southern Wide-field Gamma-ray Observatory (SWGO) is an international collaboration working on realizing a next-generation observatory located in the Southern hemisphere, which offers a privileged view of our galactic center.
Aims. Istituto Nazionale di Fisica Nucleare (INFN) is working on the construction of a prototype water Cherenkov detector at Politecnico di Milano using a flexible testing facility for several candidate light sensors and configurations.
Methods. An analytical study of extensive air showers and muons has been carried out using the HAWC observatory simulation software known as HAWCSim to examine the correlation between the detection capabilities of the prototype tank and its water level. Consequently, a level appropriate for the tests and an installation site that could handle the pressure has been determined. A structure able to hold different types of detectors in multiple configurations has been designed. A CAD model in SolidWorks has been realized for load simulations. Finally, the structure was built and tested in Politecnico’s labs.
Results. The simulations showed a linear increase in detection efficiency with the water level, as well as an increase in the number of photoelectrons (PE) detected and a reduction of the dispersion of the detection time of the first photon. The photomultipliers’ holder has been designed in two versions: a large hexagonal one capable of handling many sensor configurations and a small cross-shaped one, more simple and economical, for starting the tests with the reference configuration. The second structure has been built and tested; its pieces will be recycled for the larger one afterward. The first tests will start as soon as the tank construction is completed.
The Cosmic Ray Energetics And Mass (CREAM) experiment was developed to measure the cosmic ray elemental spectra for Z=1-26 nuclei at energies ranging from $\sim {10}^{12}$ to $\sim {10}^{15}$ eV. The balloon-borne CREAM had 7 successful flights over Antarctica and it was recently installed on the International Space Station. For energy measurements, the CREAM instrument uses a calorimeter (CAL). The CAL has 20 layers of tungsten plates interleaved with 20 layers of 50 scintillating fiber ribbons to detect showers produced by cosmic ray interactions. These ribbons are read out using 40 pixelated Hybrid Photodiodes (HPD). Each HPD consists of 73 pixels, 3 of which receive optical signals from Light Emitting Diodes (LED). These LEDs are used for checking channel aliveness and the HPD pixel-to-fiber alignment. Channel gains were measured by varying high voltages from 3 to 10.5 kV, DAC values from 6000 to 9000, and bias voltage on and off. Analysis results will be presented.
The General Antiparticle Spectrometer (GAPS) Antarctic long duration balloon mission is the first experiment optimized for the detection of low-energy cosmic antinuclei. Its novel detection technique is based on exotic atom formation, excitation, and decay, and aims to place world leading limits on viable dark matter models and inform existing models of cosmic ray propagation. There are two primary components of the GAPS instrument, designed to be highly sensitive to the rare events of interest: a large-area silicon tracker and a surrounding time-of-flight system (TOF) with near-100% hermeticity. The combination of these two systems allows GAPS to effectively differentiate between species of negatively-charged antinuclei and determine the energy deposition, velocity, and trajectory of particles interacting with the detector. This talk will briefly review the GAPS detection technique, as well as report on the status of construction of the instrument with a focus on TOF detector hardware progress. In addition, we will discuss the implementation and outcome of the GAPS functional prototype, which was assembled at the MIT Bates Research Center in October of 2021 and will continue taking data through May of 2022.
The last decade has been marked by significant progress in searches for antimatter in cosmic-rays. The unexpected abundance of positrons in the energy interval 10-200 GeV, reported by the PAMELA collaboration in 2009 and later confirmed and measured up to 1 TeV by AMS-02, remains unexplained, with nearby astrophysical sources and Dark Matter annihilation invoked as possible explanations. Even more puzzling is the observation of about 1 anti-helium isotope per year, reported by the AMS-02 collaboration, because no anti-helia from secondary production are expected to be observed by AMS-02, even in 1 century of operation.
These results are not conclusive and bring out two interrelated needs. First, to improve the quality of observations, both extending the energy range and increasing statistics. Second, to provide independent measurements of phenomena which could deeply reform our comprehension of the Universe. To meet them, new experiments are needed, featuring long-life large-acceptance high-field spectrometers, a technological challenge with few equals.
In this work I will summarize all findings about antimatter by PAMELA and AMS-02.
Afterwards, I will describe ALADInO, one of the most interesting proposals for next generation antimatter experiments, showing its scientific potential, its sensitivity and projected results. The focus will be on recent laboratory results on space-compliant high-temperature superconducting coils (HDMS project) and low-power monolithic active pixel sensors (HEPD project), paving the way towards a dedicated lightweight pathfinder mission focused on antinuclei (LAMP).
Direct measurements of cosmic rays have finally entered a precision era. Large particle physics experiments operating in space allowed high-statistic measurements of the cosmic ray energy spectra, of their chemical and isotopic composition, and of the rare anti-matter components, in a wide energy range. In this talk, I will review the progress in the field, the recent results, their implications on our understanding on the origin of cosmic rays, the new open questions, the challenges for future experiments of direct detection of cosmic rays.
Gamma-ray astronomy studies the most powerful phenomena in the Universe and tests the limits of our understanding of the laws of physics in extreme conditions. Decades of continuous improvements in experimental techniques for space-borne and ground-based observations have led to an ever-increasing sky and energy coverage. In this presentation I will discuss how the current generation of instruments including Fermi, HAWC, H.E.S.S., MAGIC, and VERITAS has marked the coming of age of gamma-ray astronomy: a growing number of different classes of emitters, more and more often studied from a population point of view, testify how non-thermal particle acceleration and transport proceed in a variety of astrophysical conditions and environments. I will also review the two developments that have revolutionized gamma-ray astronomy in recent years: the advent of multi-messenger observations with gravitational waves and neutrinos, and the opening of the ultra-high energy frontier by LHAASO that made it possible to unveil a surprisingly large number of PeV particle accelerators in the Milky Way. Finally, I will briefly talk about perspectives for unlocking even more science potential with new gamma-ray instruments, including COSI and CTA, scheduled to start operations in the next five years, and other proposed projects.
The measurement of the energy spectrum of cosmic rays is of crucial importance to reveal their origin, propagation, and acceleration mechanisms. The Pierre Auger Observatory in Argentina and the Telescope Array (TA) in the US continue to observe cosmic rays by a hybrid detector, which is composed of Fluorescence Detectors (FD) and Surface Detector (SD) array, in the southern and northern hemispheres respectively. Especially in recent measurements, they successfully measure the cosmic ray spectrum with energies below $10^{16}$ eV by observing events in which the signals from air showers are dominated by Cherenkov light by high elevation fluorescence telescopes. This contribution reviews the recent measurements by both collaborations, particularly the Cherenkov-based measurements.
The toe of the spectrum of ultra-high energy cosmic rays (UHECRs), above ~50 EeV, is an extremely interesting region for studying the origins of CRs. The potentially small magnetic deflections at these energies are coupled with the presence of the flux suppression, which could be a signature of the maximum acceleration potential of the sources, or could find its explanation in the interactions of cosmic rays with background photons, effectively limiting the region of interest in the search for UHECR sources to a relatively small bubble around us. In this talk we present the latest anisotropy searches carried out by the Pierre Auger Collaboration in the energy range above 32 EeV. The dataset used is the last collected in the ”Phase One'' of the Observatory between 2004 and 2020, before the AugerPrime upgrade, for a cumulative exposure of ~120000 km2 sr yr. We have conducted both blind, model-independent searches for overdensities, correlation analyses with astrophysical structures, and cross-correlation studies with catalogs of candidate sources. We have found evidence for a deviation from isotropy at angular scale of ~25 degrees at the 4sigma level for UHECRs with energy above 38 EeV.
The origins of the high-energy cosmic neutrino flux remain largely unknown. Last year, a high-energy neutrino was associated with the tidal disruption event (TDE) AT2019dsg by our group. I will present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino detected by IceCube. I will present observations that further support a TDE origin of this flare. These include a bright dust echo and soft late-time X-ray emission. The probability of finding two such bright events in neutrino follow-up by chance is just 0.034%. Furthermore, we have evaluated several models for neutrino production and can show that AT2019fdr is capable of producing the observed high-energy neutrino. I will also present further evidence on accretion events accompanied by luminous dust echoes being connected to high-energy neutrinos, as we have found another event with such a signature coincident with a high-energy neutrino (AT2019aalc). This reinforces the case for TDEs as neutrino sources.
The new generation of experiments for the indirect detection of cosmic radiation by observing Extensive Air Showers (EAS) in the atmosphere, requires continuous observation of the atmospheric physical properties in their Fiel of View. For this purpose, these experiments on ground and in space use large atmospheric volumes as calorimeters. One of the key points is the determination of the presence of clouds in the FoV of the infrared camera. The presence of clouds in the atmospheric detection volume modifies the transmissivity of the atmosphere producing scattering and attenuation of the fluorescence radiation generated by the secondary particles of the Extensive Air Shower on their way to the detector. We have developed a thermal space infrared camera capable of detecting the presence of clouds, determining their temperature and obtaining the Cloud Top Height (CTH). This parameter is essential for data analysis when an EAS is detected. This paper shows the analysis of the data obtained during 667N test flight of the stratospheric balloon launched by the CSBF/NASA in New Mexico.
Building on the success of IceCube at the South Pole, the next generation experiment IceCube-Gen2 is taking shape. Next to an extension of the optical array, further developing the optical detector learning for the IceCube-Upgrade currently in preparation, IceCube-Gen2 is planned to feature a large in-ice radio array targeting neutrinos beyond PeV energies. This radio array will build on heritage from many former and existing radio neutrino experiments. It will dominate the sensitivity of IceCube-Gen2 at EeV energies, improving at least an order of magnitude in sensitivity over existing arrays. IceCube-Gen2 will also feature a much enlarged surface array, including in-air radio antennas targeting air showers.
The approximation function that makes it possible to describe the lateral distribution function (LDF) of Cherenkov light of individual extensive air showers (EAS) from various primary nuclei with energies of 1-100 PeV and zenith angles up to 20 degrees with an accuracy better than 5% in the distance range 0-500 meters from the shower axis was found. Initially the approximation was intended for processing the events of the SPHERE-2 experiment, but its capabilities are clearly wider. A comparison was made with a simpler approximating function used in the SPHERE-2 processing and with the function used by the TAIGA experiment.
The Fermi Large Area Telescope is enabling a revolution in pulsar physics, having detected more than 270 gamma-ray pulsars. Many Fermi pulsars show glitches in one or more timing parameters, and one of them, the radio-quiet PSR J2021+4026, is variable on a time scale of a few years. Hence, a monitoring infrastructure is required in order to systematically study the timing evolution of gamma-ray pulsars. For this purpose we are developing the Automated Pulsar Periodicity Looker, an analysis pipeline for Fermi pulsars, based on Python and on the official Fermitools. This pipeline periodically runs data reduction and periodicity tests for each gamma-ray pulsar in the catalog, then performs a glitch search with different approaches. The computational time is reduced thanks to an optimized usage of memory, which renders the tool suitable for a systematic timing analysis of Fermi pulsars. Moreover, a web application allows users to visualize the results and to interactively manage analysis setups. Here we present a preview of the infrastructure, and we discuss future applications in the multi-messenger framework, focusing on searches for gravitational waves from pulsars.
Star-forming galaxies (SFGs) are rich in energetic cosmic rays. These CRs can undergo hadronic interactions to produce gamma-rays, with the combined gamma-ray glow from populations of SFGs forming an important component of the isotropic extra-galactic gamma-ray background (EGB). The gamma-ray emission from galaxies is dependent on their intrinsic physical properties - in particular, their star-formation rate, abundance of dense molecular gas and their size. As such, different classes of SFGs contribute differently to the EGB. In this talk, I will show that the SFG component of the EGB is dominated by starburst SFGs, while the contribution from main sequence SFGs is marginal at all energies. I will also discuss the physical characteristics of those galaxy populations which dominate the SFG contribution to the gamma-ray background, their redshift evolution, and the implications for using the EGB to probe CR engagement in SFGs over cosmic time.
The Fermi Large Area Telescope (LAT) has been in orbit of Earth since 2008 collecting gamma rays. One challenge in analyzing LAT data is detecting sources to know the various classes of gamma-ray sources and how many they are. Neural networks show impressive accuracy in many fields. Application of these networks to Fermi LAT data can potentially be more successful than traditional statistical methods of source detection. Here we present our first attempt to use a region-based convolutional neural network (Faster R-CNN) and then a Mask R-CNN, which has built-in instance segmentation, something that networks previously applied to data lack. We have generated three training and test datasets of simulated Fermi LAT images with different parameters such as noise and photon counts. These were used to separately train Facebook AI's Mask R-CNN model with a ResNet-50 backbone and feature pyramid network for instance segmentation of sources. We found this method to be promising and we present here our preliminary results.
Interactions between secondary cosmic rays and nuclei in natural minerals can leave tracks in the lattice due to nuclear recoils. These defects can be preserved up to the Gyr timescale, making these so-called “Paleo-detectors” useful “time machines” for the study of the history of astrophysical messengers such as cosmic rays, neutrinos or even dark matter. These "Paleo-detectors" feature huge accumulated exposure times even for small masses of material, making them long-term flux integrators of all radiation along the evolution of our planet. We present the case study of the Messinian salinity crisis, a period of draining of the Mediterranean Sea which is interestingly coincident with the estimated age of the Fermi Bubbles, around 5.5 Myr ago, when our Galaxy might have been active. Greatly increased cosmic ray acceleration near the Galactic Center could have left traces in the evaporites, mainly Halite, created with the evaporation of the sea and exposed directly to secondary cosmic rays. These mineral structures were then covered during the sudden reflooding of the Mediterranean basin 5.3 Myr ago; the cosmic ray flux information remained frozen due to the shielding of the massive body of water, possibly retaining information on the flux of particles at ground in that epoch.
The transport of charged particles in various astrophysical environments permeated by magnetic fields is described in terms of a diffusion process, which relies on diffusion-tensor parameters generally inferred from Monte Carlo simulations. In this contribution, a theoretical derivation of the diffusion coefficients is presented. The approach, based on a few approximations to model the 2-point correlation function of the magnetic field experienced by the particles between two successive times, is shown to describe both the high-rigidity regime, in which the Larmor radius is greater than the larger wavelength of the turbulence, and the gyroresonant regime regime, in which the Larmor radius of the particles is in resonance with the wavelength power spectrum of the turbulence. The results are shown to be consistent with those obtained with a Monte Carlo generator.
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 2.0 TeV based on 50 million electrons collected by the Alpha Magnetic Spectrometer on the International Space Station. In the entire energy range the electron and positron spectra have distinctly different magnitudes and energy dependences. At medium energies, the electron flux exhibits a significant excess starting from 49.5 GeV compared to the lower energy trends, but the nature of this excess is different from the positron flux excess above 24.2 GeV. At high energies, our data show that the electron spectrum can be best described by the sum of two power law components and a positron source term. This is the first indication of the existence of identical charge symmetric source term both in the positron and in the electron spectra and, as a consequence, the existence of new physics.
The creation of anti-nuclei in the Galaxy has been has been discussed as a possible signal of exotic production mechanisms such as primordial black hole evaporation or dark matter decay/annihilation in addition to the more conventional production from cosmic-ray (CR) interactions with the gas in the interstellar medium. Excitingly, other astrophysical excesses that have been correlated with dark matter (e.g., GCE, DAMA, etc.), predict an antinuclei flux that is within the sensitivity range reached by detectors such as AMS-02 and GAPS in the coming years. In addition, the detection of anti-nuclei produced from CR interactions can also be achievable in a mid-to-short term.
In this talk, we present a study of the anti-nuclei production expected from a global analysis of CRs involving antiprotons and considering dark matter. We compare those predictions with the sensitivity expected from CR experiments in the next years and discuss the uncertainties related to current nuclear models of anti-nuclei production and astrophysics.
Analysis of anisotropy of the arrival directions of galactic protons, helium, carbon and oxygen has been performed with the Alpha Magnetic Spectrometer on the International Space Station. These results allow to investigate the origin of the spectral hardening observed by AMS in these cosmic ray species. The AMS results on the dipole anisotropy are presented along with the discussion of the implications of these measurements.
Cosmic Rays (CR) inside the Heliosphere interact with the solar wind and with the interplanetary magnetic field, resulting in a temporal variation of the cosmic ray intensity near Earth for rigidities up to a few tens of GV. This variation is known as Solar Modulation. Previous AMS results on proton and helium spectra showed how the two fluxes behave differently in time. To better understand these unexpected results, one could therefore study the next most abundant species. In this contribution, the precision measurements of the monthly proton, helium, carbon, and oxygen fluxes for the period from May 2011 to Nov 2019 with the Alpha Magnetic Spectrometer on the International Space Station are presented. The detailed temporal variations of the fluxes are shown up to rigidities of 60 GV. The time dependence of the C/O, He/(C+O), p/(C+O), and p/He are also presented, and their implication on the shape of the nuclei LIS is discussed.
We present RDSim, a fast and comprehensive framework for the simulation of the radio detection of downgoing air showers. It can handle any downgoing shower that can be simulated with ZHAireS, including those induced by CC and NC neutrino interactions and $\tau$ decays. RDSim is based on a superposition toymodel that disentangles the Askaryan and geomagnetic components of the shower emission. By using full ZHAireS simulations as input, it is able to estimate the radio footprint anywhere on the ground. A single input simulation at a given energy and arrival direction can be scaled in energy and rotated in azimuth by taking into account all relevant effects. This makes it possible to simulate a huge number of geometries and energies using just a few ZHAireS input simulations.
The framework takes into account the main characteristics of the detector, such as trigger setups, thresholds and antenna patterns. To accommodate arrays that use particle detectors for triggering, such as the Auger RD extension, it also features a second toymodel to estimate the muon density at ground level, which is used to perform simple particle trigger simulations.
It's speed makes it possible to investigate in detail events with a very low trigger probability, as well as many geometrical effects, such as those due to asymmetric arrays, infills and other border effects. In case more detailed studies of the radio detection are needed, RDSim can also be used to sweep the phase-space for the efficient creation of dedicated full simulation sets. This is particularly important in the case of neutrino events, that have extra variables that greatly impact shower characteristics, such as interaction or $\tau$ decay depth as well as the type of interaction and it's fluctuations.
TeV halos have become a new class of astrophysical objects which were not predicted before their recent observation. They offer evidence that diffusion around sources (concretely, pulsars) is not compatible with the effective average diffusion that our models predict for the Galaxy. This directly impacts Galaxy formation, our knowledge of the propagation process throughout the Galaxy and our models of acceleration of charged particles by astrophysical sources like supernova remnants (SNRs) or Pulsar Wind Nebulae (PWN).
In this talk we show that, while anisotropic models may explain a unique source such as Geminga, the phase space of such solutions is very small and they are unable to simultaneously explain the size and approximate radial symmetry of the TeV halo population. Furthermore, we note that this conclusion holds for any CR-powered source (hadronic or leptonic), implying more generally that anisotropic diffusion does not dominate the propagation of particles near energetic sources (at least, below hundreds of TeV) because of the self-generated turbulence.
The Tibet ASgamma and LHAASO collaborations recently reported the observation of a gamma-ray diffuse emission from the Galactic plane with energy up to the PeV.
We show that under physically motivated conditions these results, together with those of Fermi-LAT and ARGO-YBJ at lower energies, can consistently be interpreted in terms of an emission originated by the Galactic cosmic-ray (CR) population, the so called “CR sea”.
Our analysis favour CR transport models characterised by spatial-dependent diffusion although some degeneracy remains between the choice of the transport scenario and that of the CR spectral shape above 10 TeV. We discuss the possible relevance of forthcoming measurements, especially those performed by experiments located in the South hemisphere, in resolving that ambiguity. We will then present examples of high resolution maps and spectra of the simulated gamma-ray diffuse emission of the Galaxy from few GeV up to the PeV which we release and can be used by experimental collaborations as templates.
(based on https://arxiv.org/abs/2203.15759 )
High performant shower discriminators are crucial in the pursuit of PeVatron gamma-ray events. In this contribution, we introduce a novel gamma/hadron discriminating variable that quantifies the azimuthal non-uniformity of the particle distributions at the ground.
The proposed quantity has been tested for showers with energies between $10\,$TeV and $1\,$PeV and detector arrays with different fill factors, showing a remarkable discrimination power, similar to the one obtained by estimating the shower muon content. Such implies that the azimuthal non-uniformity in the shower pattern can be an alternative to access the intrinsic differences in the development of electromagnetic and hadronic showers without implementing any costly strategy to absorb the electromagnetic component of the shower.
Additionally, we show that it exhibits a strong correlation with the number of muons at the ground, making it an exceptional tool for studying shower hadronic interactions and the cosmic ray primary composition.
Finally, in this presentation, I shall discuss how this quantity might be easily accessed in present ground-array gamma-ray observatories and how it may significantly increase the effective area of future ones.
Gamma-ray observations by Fermi LAT in nearby clouds have shown that the cosmic-ray flux within 500 pc around the Sun is fairly uniform except in the Eridu cloud, which exhibits a puzzling 30 % drop in gamma-ray emissivity per gas atom. The magnetic field in this filamentary cloud is well aligned with the cloud axis and points towards the halo. In the case of anisotropic diffusion, cosmic rays would stream along the filament towards high altitudes above the Galactic plane.
We have therefore compared the gamma-ray emissivity in Eridu with that expected from the cosmic-ray flux incident on the heliosphere. We have also studied the gamma-ray flux recorded in another nearby, highly-inclined filamentary cloud. The magnetic field in this Reticulum cloud is also well ordered, aligned with the filament, and oriented towards the halo.
We have found that, because of 20-30 % systematic uncertainties between hadronic cross sections for gamma-ray production, we cannot conclude whether the cosmic-ray flux in Eridu is consistent or not with the flux at the Sun.
We find a gamma-ray emissivity in Reticulum that is close to the local average rather than to the low value in Eridu. The difference between the two filaments provides an important test case to study cosmic-ray transport in diffuse clouds and ordered magnetic fields.
Standard models of the large-scale interstellar emission officially adopted so far for studies of the Fermi-LAT data are very uncertain and show some discrepancies with respect to the data especially in the inner Galaxy where the degeneracy with the various components is large, underlining the necessity of more realistic models.
We focus here on the large-scale Inverse Compton component of the interstellar emission, which is produced by cosmic-ray electrons and positrons on the CMB and interstellar photons. We have updated the inverse-Compton models accounting for latest precise cosmic-ray measurements, with AMS02 and Voyager, and for a more realistic magnetic field model consistent with synchrotron emission, which is observed in radio and microwaves, produced by the same electrons and positrons. We show the effects of such improvements in the spectral and spatial distribution of the inverse-Compton models.
We found that the updated 3D magnetic field model, which we constrain by synchrotron observations, produces a more peaked inverse-Compton emission in the inner Galaxy with respect to the standard models used to analyze Fermi LAT data so far. Predictions for future missions at MeV, such as GECCO, AMEGO, and ASTROGAM are also shown.
The $\gamma$-ray spectrum of the Galactic source HAWC J1825-134 measured with HAWC [Albert et al., ApJ Lett., 907, L30 (2021)] extends beyond 200 TeV and does not reveal a knee or a cutoff. HAWC J1825-134 is among the best candidates for hadronic PeVatrons --- the objects able to accelerate protons up to the energy of at least 1 PeV. However, this source is situated in a crowded region of the $\gamma$-ray sky, greatly complicating the analysis.
Using the publicly available dataset of the Fermi-LAT space $\gamma$-ray telescope, we dissect the region around HAWC J1825-134 and eventually derive upper limits on the intensity of the source in the 1 GeV--1 TeV energy range. We show that only a very hard ($\gamma_{p}$<1.5) primary proton spectrum at $E_{p}$<10 TeV describes the Fermi-LAT data set well. Very hard $\gamma$-ray spectra below several TeV could represent a useful signature of Galactic hadronic PeVatrons.
A simple power-law-exponential cutoff spectrum could in principle describe the combined HAWC and Fermi-LAT data sets reasonably well for $\gamma_{p}\approx$1.5 and the cutoff energy $E_{p-c}\approx$500 TeV. More details could be found in [Dzhatdoev et al., ApJ, 929, 25 (2022)].
O Deligny1, I Lhenry-Yvon1, Q Luce2, M Roth2, D Schmidt2 and A A Watson3
1 IJClab (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie), CNRS/IN2P3, Université Paris-Saclay, Orsay, France 2 Institut für Astroteilchenphysik (IAP), Karlsruhe Institute of Technology, Karlsruhe, Germany 3 School of Physics and Astronomy, University of Leeds, LS2 9JT, UK
When analysing data from air-shower arrays, it has become common practice to use the signal at a considerable distance from the shower axis (r_opt) as a surrogate for the size of the shower. This signal, S(r_opt), can then be related to the primary energy in a variety of ways. After a brief review of the reasons for the introduction of r_opt, made in a seminal paper by Hillas in 1969, it will be shown that r_opt is a more effective tool when the detectors are laid out on a triangular grid than when the detectors are deployed on a square grid. This result may have implications for explaining the differences of flux observed above 10 EeV by the Auger and Telescope Collaborations. Additionally, this finding should be kept in mind when designing new shower arrays.
Simulations of extensive air showers using current hadronic interaction models predict too small number of muons compared to events observed in the air shower experiments, which is known as the muon deficit problem. In this work, we present a new method to calculate the factor by which the muon signal obtained via Monte-Carlo simulations must be rescaled to match the data, as well as the β exponent from the Heitler-Matthew’s model which governs the number of muons found in an extensive air shower as a function of the mass and the energy of the primary cosmic ray. This method uses the so-called z variable (difference between the total reconstructed and the simulated signals), which is connected to the muon signal and is roughly independent of the zenith angle, but depends on the mass of the primary cosmic ray. Using a mock dataset built from QGSJetII-04, we show that such a method allows us to recover the muon signal from this dataset using Monte-Carlo events generated with the EPOS-LHC hadronic model, within less than 6% on average, and the average β exponent for the studied system, within less than 1%, which is a consequence of the good recovery of the muon signal for each primary included in the analysis. Detailed simulations show a dependence of the β exponent on hadronic interaction properties, thus the determination of this parameter is important for understanding the muon deficit problem.
The IceCube Neutrino Observatory at the South Pole can provide unique tests of muon production models in extensive air showers by measuring both the low-energy (GeV) and high-energy (TeV) muon components. We present here a measurement of the TeV muon content in near-vertical air showers detected with IceTop in coincidence with IceCube. The primary cosmic-ray energy is estimated from the dominant electromagnetic component of the air shower observed at the surface. The high-energy muon content of the shower is studied based on the energy losses measured in the deep detector. Using a neural network, the primary energy and the multiplicity of TeV muons are estimated on an event-by-event basis. The baseline analysis determines the average multiplicity as a function of the primary energy between 3 PeV and 300 PeV using the hadronic interaction model Sibyll 2.1. Results obtained using simulations based on the post-LHC models QGSJet-II.04 and EPOS-LHC are presented for primary energies up to 100 PeV. For all three hadronic interaction models, the measurements of the TeV muon content are consistent with the predictions assuming recent composition models. Comparing the results to measurements of GeV muons in air showers reveals a tension in the obtained composition interpretation based on the post-LHC models.
The predictions of high energy hadronic interaction models for hadron induced air showers contain significant systematic uncertainties due to the limits of both accelerator data and theoretical descriptions in the appropriate energy and rapidity ranges. Tuning for these models is typically performed to reproduce cosmic-ray data above 10$^{15}$ eV, with energies below this often not being prioritised.
We will present detailed studies of hadronic air shower simulation predictions in the 100 GeV to 100 TeV energy range typically studied by very high energy gamma-ray telescopes. We describe the significant differences seen in important model predictions, most notably at the lower energy edge of the model validity (100 GeV). Finally we take a closer look at simulations of the discrete interactions within the air showers to try to correlate the differences in interaction physics between models with those seen in air shower behaviour.
We present a novel semi-analytical treatment of the radio emission of air showers that is able to reproduce the results of full ZHAireS simulations, in theory at a fraction of the computational cost. Traditionally, the contribution to the vector potential of every single particle track in the shower is calculated separately. Instead, in our approach we divide the air shower into 4-D spacetime volumes, so that the contribution of the whole bin needs to be calculated only once, based on the average particle track inside it. This almost amounts to a macroscopic treatment of the shower, but retaining the precision of the successful microscopic approach.
The size of the 4-D spacetime volumes is chosen so that the traditional vector potential expression can be further simplified, as many of its terms can be taken to be the same for the whole bin. Computationally expensive terms, such as the the effective refractive index from the track to the observer, can then be calculated only once, making it possible to obtain the precise radio emission at a fraction of the cost.
This approach also allows us to perform more precise calculations that would otherwise be too expensive to apply on a track-by-track basis. These could include a more detailed treatment of atmospheric effects for near horizontal showers and high altitude detectors, such as balloons and satellites.
The Fortran-versions of the CORSIKA air shower simulation code have been at the core of simulations for many astroparticle physics experiments for the last 30 years. Having grown over decades into an ever more complex software, maintainability of CORSIKA has become increasingly difficult, though its performance is still excellent. Since 2018, therefore a complete rewrite of CORSIKA has begun in modern modular C++. Today, CORSIKA 8 has reached important milestones with a full-fledged implementation of both the hadronic and electromagnetic cascades, the ability to simulate radio and Cherenkov-light emission from air showers and an unprecedented flexibility to configure simulation media and their geometries.
This presentation will discuss the current status of CORSIKA 8, highlight the new possibilities already available, and future prospects of this new air shower simulation framework.
The study of cosmic-ray (CR) composition plays an important role in determining their origin and acceleration mechanism. In the TeV energy range, space experiments perform composition measurements that identify incoming particles and measure the energy accurately. Ground-based experiments can provide a complementary measurement of the mass composition by studying air showers. The depth of the shower maximum, referred to as Xmax, depends on the mass of the primary particle and on its energy. Thus, developing techniques to measure the Xmax of a collection of air showers offer possibilities for the CR composition. The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for high-energy gamma-ray astronomy. With several tens of telescopes in the northern and southern hemispheres, CTA will be the most sensitive ground-based observatory for gamma-ray energies.
In this work, we present a novel approach that uses IACTs (Imaging atmospheric Cherenkov telescopes) to reconstruct the shower profile of cosmic-ray and gamma-ray air showers in the TeV range. Using a parametric description of the angular distribution of the Cherenkov light emitted along the shower axis, we propose a novel method for reconstructing the shower longitudinal profile and the Xmax on an event-by-event basis. Preliminary estimates based on a simplified detector geometry indicate that this method provides a resolution on the Xmax of the order of 30 g/cm2 at 100 TeV. We apply our approach to simulated air showers detected by the upcoming Cherenkov Telescope Array. We focus on showers initiated by three different types of primary particles: gamma rays, protons, and iron nuclei.
The IceCube Neutrino Observatory is a cubic kilometer scale detector deployed
in the Antarctic ice. The surface array of IceCube, IceTop, serves as an
air-shower detector for primary cosmic rays in the PeV energy range and operates
as a veto and calibration detector for the astrophysical neutrino searches
for the IceCube in-ice instrumentation. Enhancing IceTop with a hybrid array
of scintillation detectors and radio antennas will lower the energy threshold for
air-shower measurements, provide more efficient veto capabilities, enable the
separation of the electromagnetic and muonic shower components, and significantly
improve the detector calibration by compensating for snow accumulation.
A prototype station consisting of 3 radio antennas and 8 scintillation detectors
was deployed at the South pole in 2020, and has yielded promising results
since. The production of the full surface array enhancement is ongoing. In
this contribution we will focus on the status of the production and calibration
methods for the scintillation panels. A brief introduction to the expected data
and proposed analysis from the enhancement is also discussed.
Technological breakthroughs in telescope development have always driven discoveries in astrophysics. Discoveries are yet to be made in the energy band between a few hundreds keV and a few MeV, which is currently very little explored due to the lack of sensitive enough telescopes. In this band the telescope technology is challenged by the changing nature of the photon-matter interaction used to detect the astrophysical radiation. To address this issue, the Galactic Explorer with a Coded Aperture Mask Compton Telescope (GECCO) features a coded-mask telescope and a Compton telescope. The former allows disentangling sources in crowded regions with its high angular resolution of ~1 arcmin, which is complemented by the latter due to its high sensitivity to the diffuse emission. The ability to tell the diffuse and point sources apart allows exploring the acceleration of cosmic-rays, the origin of the so-called Fermi Bubbles, the 511 keV positron annihilation line, sites of explosive element synthesis, and testing for dark matter candidates. Also different classes of jetted galaxies that display a peak of power output in this unexplored energy range are a major target for GECCO to understand how their central supermassive black holes evolve over cosmic time and how they accelerate particles.
The study of how cosmic rays (CRs) interact with the Earth’s magnetic environment is heavily reliant on simulations of CRs trajectories within the Earth’s magnetosphere. These simulations are computationally taxing and require the use of sophisticated programs, with MAGNETOCOSMICS being the most used tool currently. MAGNETOCOSMICS, while functional, fast, and reliable, is outdated (requiring software that is no longer supported to function) and offers limited flexibility for experimentation beyond its initial parameters. The development of a new open access magnetospheric tool benefits the CR research community greatly, allowing for easier testing of new models. Using freely available pre-made code and magnetic field models for the magnetosphere a more user-friendly tool for magnetospheric computations was created. The FORTRAN and Python computing languages are used as the basis of the tool .
The tool can conduct large scale computations of particle trajectories, cut-off rigidities, and asymptotic cones of acceptance. The calculations conducted by the new tool have a good agreement with previous results obtained by MAGNETOCOSMICS. The close agreement between prior tools and this modern code shows clear promise in the new program. The future open access nature of the tool will also allow further improvements to the computational accuracy and speed as more researchers add to the existing code. Ideally the tool will provide the groundwork for a community driven magnetospheric tool that will be used throughout the community.
NUSES is a new space mission project promoted by the Gran Sasso Science Institute (GSSI) in collaboration with the Italian National Institute of Nuclear Physics (INFN) and Thales Alenia Space Italy (TAS-I), devoted to the exploration of new technologies and observational approaches for space based cosmic ray studies. The mission consists of two detectors operating onboard the NUSES satellite: TERZINA and ZIRE'.
TERZINA is a pathfinder Cherenkov telescope for the study of EAS induced by high energy cosmic rays and astrophysical, Earth skimming, neutrinos, with a focal plane made by SiPMs. The use of SiPMs will be exploited also for the ZIRE` payload, mainly devoted to flux measurements of electrons, protons and light nuclei with energies spanning from few up to hundreds of MeVs, but also operating with a novel concept as cosmic MeV gamma ray detector. A further objective for ZIRÉ will be the study of space weather phenomena and of possible correlations among seismic activity on ground and low energy electrons and proton fluxes due to magnetosphere-ionosphere-lithosphere coupling (MILC).
This contribution will give an overview about the scientific goals, the adopted technologies and the status of the ongoing activities.
At present time the behavior of electron spectrum at energies more than 1 TeV induce significant interest in view of the contradictory results concerning the presence of the cut-off.
GAMMA-400 gamma-ray telescope with lateral size of calorimetr ~43 Xo will be able to extend the measurements of electron fluxes up to 20 TeV and to verify the data of previous experiments at several TeV energies. The results of presented simulations the provide electron/proton rejection factor at the level of 10 4 . This estimation was obtained using a multivariate analysis based on boosted decision trees (B Ts). This analysis provide the value of the lateral acceptance ~0.1 m 2 sr for each lateral side and for the energies more than 100 GeV.
The Schwarzschild-Couder Telescope (SCT) is a Medium-Sized Telescope proposed for the Cherenkov Telescope Array (CTA). The first prototype (named pSCT) has been constructed and is being commissioned at the Lawrence Whipple Observatory in Arizona, USA. The SCT is characterized by a dual-mirror optical design to remove the comatic aberrations across its field of view. The pSCT camera is now partially equipped with Silicon Photomultiplier (SiPM) matrices produced by Fondazione Bruno Kessler (FBK) and is now in the upgrade phase. A new design of the front-end electronics (FEE) based on the TARGET ASICs will be installed to obtain an improvement especially in the noise performance. The new FEE design will also include a 16-channel integrated pre-amplifier, called SMART, developed, and tested by INFN to match the signal produced by the FBK SiPMs.
The results of the performance of the SMART ASIC coupled to the FBK SiPMs and to the new FEE modules will be shown in terms of gain and noise.
The existence of cosmic accelerators able to emit charged particles up to ZeV energies has been confirmed by the observations made in the last years by experiments such as Auger and Telescope Array. The interaction of such energetic cosmic-rays with gas or low energy photons, surrounding the astrophysical sources or present in the intergalactic medium, guarantee an ultra-high-energy neutrino related emission. When these energetic neutrinos interact in a medium produce a thermo-acoustic process where the energy of generated particle cascades can be conveyed in a pressure pulse propagating into the same medium. The kilometric attenuation length as well as the well-defined shape of the expected pulse suggest a large-area-undersea-array of acoustic sensors as an ideal observatory. For this scope, we propose to exploit the existing and no more operative offshore (oil rigs) powered platforms in the Adriatic sea as the main infrastructure to build an acoustic submarine array of dedicated hydrophones covering a surface area up to 10000 km$^{2}$ and a volume up to 500 km$^3$. In this work we describe the advantages of this detector concept using a ray tracing technique as well as the scientific goals linked to the challenging purpose of observing for the first time ultra-high-energy cosmic neutrinos. This observatory will be complementary to the dedicated radio array detectors with the advantages of avoiding any possible thermo-acoustic noise from the atmospheric muons.
The field of extreme space weather has undergone substantial development during the past 20 years, beginning in 2003 with the uncovering of magnetic records from India for the 1859 Carrington storm. More recently, new windows on extreme solar-terrestrial events have opened with studies of cosmogenic nuclide events and historical aurorae and the discovery of superflares on solar-type stars. Here we consider the observed, inferred, and estimated limits of space weather phenomena, including solar flares, solar energetic particle events, coronal mass ejections, and magnetic storms.
The Sun drives a supersonic wind which inflates a giant plasma bubble in our very local interstellar neighborhood, the heliosphere. Its boundaries and the turbulent magnetic field shield the solar system from much of the interstellar medium as well as the low-energy portion of galactic cosmic rays (GCRs) which are accelerated primarily by super-nova-driven shocks in our galaxy. The heliosphere is bathed in an extremely variable background of energetic ions and electrons which originate from a number of sources. Solar energetic particles (SEPs) are accelerated in the vicinity of the Sun, whereas shocks driven by solar disturbances are observed to accelerate energetic storm particles (ESPs). Moreover, a dilute population with a distinct composition forms the anomalous cosmic rays (ACRs) which are of a mixed interstellar-heliospheric origin. Particles are also accelerated at planetary bow shocks.
In February 2020, the European Space Agency (ESA) launched Solar Orbiter, a science mission to answer the question how the Sun creates and controls the heliosphere. Its orbit brings it within 0.3 astronomical units (au) from the Sun and will also reach moderately high solar latitudes to allow to understand why solar activity changes with time. The spacecraft carries instruments which observe the Sun and its surrounding remotely, others that measure the local environment, and one which can track solar disturbances as they travel away from the Sun.
The Energetic Particle Detector (EPD) on Solar Orbiter measures suprathermal and energetic particles in the energy range from a few keV up to (near-) relativistic energies (few MeV for
electrons and about 500 MeV nuc −1 for ions). Together with the other sophisticated instruments on Solar Orbiter it is designed to unravel how solar eruptions produce energetic particle radiation that fills the heliosphere.
Since launch, EPD has made several advances about GCRs, SEPs, ACRs, ESPs, and the particles around the Venusian magnetosphere.
While the Antares undersea neutrino telescope has been decommissioned this year - after 15 years of continuous data taking - the KM3NeT neutrino telescopes are well underway in their construction in the same, deep, Mediterranean waters. The main scientific goals of the KM3NeT detectors are finding and studying sources of high-energy (TeV-PeV) neutrinos with KM3NeT/ARCA (Astroparticle Research with Cosmics in the Abyss), and determining the ordering of the neutrino masses using GeV energy atmospheric neutrinos with KM3NeT/ORCA (Oscillations Research with Cosmics in the Abyss). The Antares telescope and the KM3NeT detectors use the same principle for neutrino detection. By instrumenting large volumes of seawater with photo-multiplier tubes, the Cherenkov light from charged products of neutrinos interactions can be detected. While Antares used large, 10-inch PMTs, the KM3NeT detectors have improved upon this concept and concentrate 31 3-inch PMTs in the same glass spheres. In their final configurations, the ORCA telescope will densely instrument about 7 megatonnes of sea-water, and the ARCA telescope about a gigatonne in a less dense configuration. While growing in size, the ORCA and ARCA telescopes have already provided data and measurements, showing their capabilities. The science programme of the Mediterranean telescopes also includes multi-messenger astronomy, dark matter and exotics searches, and cosmic-ray physics. In this talk, selected results of Antares will be presented, together with the status and results from the growing ORCA and ARCA detectors, which carry on the Antares legacy with an improved energy range, resolution, and sensitivity.
The field of neutrino telescopes is continuously growing and better and more experimental data is becoming available. Besides the continuing interest in neutrino astronomy, these detectors can also be used for particle physics. In particular are neutrino telescopes complementary to lab based experiments, such as accelerators, offering different energy ranges and coming with different sources of systematic uncertainties.
In this talk I will highlight recent results, in particular for neutrino oscillations within the standard 3-flavour paradigm and beyond, and explore some exciting future directions.
I will discuss various ways in which we can try to probe axion physics using the magnetospheres of neutron stars. I will focus in particular on two distinct possibilities: (i) the identification of radio lines coming from the resonant conversion of axion dark matter, and (ii) the possibility of sourcing axions directly from the plasma dynamics in the polar caps of neutron stars. I will show that both of these processes give rise to strong observational signatures that can probe novel axion parameter space.
The last years have been dense with new developments in the search for the sources of Galactic cosmic rays (CRs): 1) The detection of features in the spectra of some primary chemicals opened new questions on the propagation of CRs in the Galaxy. 2) Precise measurements by AMS-02 of secondary nuclei are providing unique information about the transport processes over a larger energy domain 3) HESS, CALET and DAMPE have reported substantial steepening of the total lepton spectrum at ∼TeV with a spectral index softening by about 1. In my talk, I will discuss some of these developments and their implications for our understanding of the origin of cosmic rays.
The newly launched eRosita X-ray satellite revealed two gigantic bubbles above and below the Galactic center. The "eRosita bubbles" bare a remarkable resemblance to the Fermi bubbles detected in gamma rays, suggesting a common origin. The physical origin of these giant Galactic bubbles has been hotly debated. Using 3D magnetohydrodynamic simulations including relevant cosmic-ray physics, we show that the multi-wavelength observational data of the gamma-ray/X-ray bubbles as well as the microwave haze could be simultaneously explained by a single event of jet activity of Sgr A* about 2.6 million years ago. I will highlight some of the important constraints derived from our simulations and discuss the implications of the results on galaxy-scale AGN feedback in general.
In 2012, during the centennial year of the discovery of cosmic rays, Voyager 1 crossed the heliopause and began making the very first in-situ observations of the surrounding interstellar medium. Joined by Voyager 2 in 2018, these twin spacecraft continue to provide critical measurements of cosmic rays in a surprising, previously-unexplored plasma regime from distinct vantage points. This talk will address key results from nearly a decade of cosmic ray measurements in the Very Local Interstellar Medium, focusing on the low-energy end of the spectrum (X to about 1 GeV). We will highlight such topics as: 1) the local interstellar cosmic ray spectra, 2) the boundary for solar modulation, 3) shock-related intensity enhancements linked to Sun-caused transients, and 4) unanticipated, long-lived episodes of pitch-angle anisotropy. Lastly, we discuss the implications of the Voyager’s in-situ measurements in relation to recent advances in understanding about the global heliosphere, informed by over a decade of concurrent observations from NASA’s Interstellar Boundary Explorer (IBEX).