Speaker
Description
Due to their scientific importance, e.g., in the fields of nuclear physics and cosmology, the scientific community is eagerly waiting to detect more neutron star mergers.
Motivated by this, we study the gravitational-wave trigger GW231109_235456, a sub-threshold neutron star merger candidate observed in the first part of the fourth observing run of the LIGO–Virgo–KAGRA collaboration.
Assuming the trigger is of astrophysical origin, we analyze it using state-of-the-art waveform models and investigate the robustness of the inferred source parameters under different prior choices in Bayesian inference.
Using our findings, we assess the implications for the nuclear equation of state.
Combining GW170817 and GW190425 with GW231109_235456, we estimate that the radius of a $1.4\,M_\odot$ neutron star should be $R_{1.4} = 12.07^{+1.08}_{-1.19}$ km, compared to $12.21^{+1.06}_{-1.37}$ km from GW170817 alone, at the $90\%$ credible level.
We find that the remnant most likely collapsed promptly to a black hole and that, because of the large distance, a possible kilonova connected to the merger was noticeably dimmer than AT2017gfo.
In our projections for the future, we simulate a similar event using the upcoming generation of gravitational-wave detectors. Our findings indicate that we can constrain the neutron star radius with an accuracy of 400 meters using the Einstein Telescope alone, or 300 meters when combined with the Cosmic Explorer, both at $90\%$ credibility.
