Perspectives for multi-messenger astronomy with the next generation of gravitational-wave detectors and high-energy satellites

TL;DR

This paper discusses how next-generation gravitational-wave detectors and high-energy satellites will revolutionize multi-messenger astrophysics by enabling near-complete joint detection of binary neutron star mergers and their electromagnetic counterparts, especially in the X-ray and gamma-ray bands.

Contribution

It provides a theoretical framework predicting high-energy emission detectability from BNS mergers and evaluates joint detection rates with future GW and high-energy observatories.

Findings

Joint GW and gamma-ray detection efficiency approaches 100% with third-generation GW networks.

Wide field X-ray monitors significantly improve electromagnetic counterpart identification.

Future X-ray observatories will probe low-luminosity SGRBs and jet structures.

Abstract

The Einstein Telescope (ET) is going to bring a revolution for the future of multi-messenger astrophysics. In order to detect the counterparts of binary neutron star (BNS) mergers at high redshift, the high-energy observations will play a crucial role. Here, we explore the perspectives of ET, as single observatory and in a network of gravitational-wave (GW) detectors, operating in synergy with future $\gamma$-ray and X-ray satellites. We predict the high-energy emission of BNS mergers and its detectability in a theoretical framework which is able to reproduce the properties of the current sample of observed short GRBs (SGRB). We estimate the joint GW and high-energy detection rate for both the prompt and afterglow emissions, testing several combinations of instruments and observational strategies. We find that the vast majority of SGRBs detected in $\gamma$-rays will have a detectable GW counterpart; the joint detection efficiency approaches $100\%$ considering a network of third generation GW observatories. The probability of identifying the electromagnetic counterpart of BNS mergers is significantly enhanced if the sky localisation provided by GW instruments is observed by wide field X-ray monitors. We emphasize that the role of the future X-ray observatories will be very crucial for the detection of the fainter emission outside the jet core, which will allow us to probe the yet unexplored population of low-luminosity SGRBs in the nearby Universe, as well as to unveil the nature of the jet structure and the connections with the progenitor properties.