Speaker
Description
The GeV gamma-ray sky, as observed by the Fermi Large Area Telescope (Fermi LAT), harbours a plethora of localised point-like sources. At high latitudes ($|b| >30^{\circ}$), most of these sources are of extragalactic origin. The source-count distribution as a function of their flux, $\mathrm{d}N/\mathrm{d}S$, is a well-established quantity to summarise this population. We employ sequential simulation-based inference using the truncated marginal neural ratio estimation (TMNRE) algorithm on 15 years of Fermi LAT data to infer the $\mathrm{d}N/\mathrm{d}S$ distribution between 1 and 10 GeV in this part of the sky. While our approach allows us to cross-validate existing results in the literature, we demonstrate that we can go further than mere parameter inference. We derive a source catalogue of detected sources at high latitudes in terms of position and flux obtained from a self-consistently determined detection threshold based on the LAT's instrument response functions and utilised gamma-ray background models.
