Searching for very-high-energy electromagnetic counterparts to gravitational-wave events with the Cherenkov Telescope Array

TL;DR

This paper discusses how the Cherenkov Telescope Array can be used to detect very-high-energy electromagnetic signals from gravitational-wave events, especially short gamma-ray bursts linked to neutron star mergers, enhancing multi-messenger astronomy.

Contribution

It presents the CTA GW follow-up program and explores observational strategies for detecting VHE EM counterparts to GW events, focusing on short GRBs associated with BNS mergers.

Findings

CTA's sensitivity and rapid response improve VHE EM counterpart detection prospects.

Optimal observational strategies for GW follow-up are outlined.

Prospects for detecting VHE signals from GW events are promising.

Abstract

The detection of electromagnetic (EM) emission following the gravitational wave (GW) event GW170817 opened the era of multi-messenger astronomy with GWs and provided the first direct evidence that at least a fraction of binary neutron star (BNS) mergers are progenitors of short Gamma-Ray Bursts (GRBs). GRBs are also expected to emit very-high energy (VHE, > 100 GeV) photons, as proven by the recent MAGIC and H.E.S.S. observations. One of the challenges for future multi-messenger observations will be the detection of such VHE emission from GRBs in association with GWs. In the next years, the Cherenkov Telescope Array (CTA) will be a key instrument for the EM follow-up of GW events in the VHE range, owing to its unprecedented sensitivity, rapid response, and capability to monitor a large sky area via scan-mode operation. We present the CTA GW follow-up program, with a focus on the searches for short GRBs possibly associated with BNS mergers. We investigate the possible observational strategies and we outline the prospects for the detection of VHE EM counterparts to transient GW events.