The capability of the Australian Square Kilometre Array Pathfinder to detect prompt radio bursts from neutron star mergers

TL;DR

This paper evaluates ASKAP's potential to detect prompt radio bursts from neutron star mergers associated with gravitational wave events, highlighting observational strategies and the impact of alert timing on detection prospects.

Contribution

It introduces a simulation-based assessment of ASKAP's ability to detect prompt radio emissions from neutron star mergers during upcoming gravitational wave observing runs, considering alert timing and sky localization.

Findings

ASKAP's fly's eye mode covers large sky areas suitable for prompt emission detection.

Detection likelihood is low, with an estimated 0.012 events in the fourth run.

Pre-merger alerts improve chances of capturing prompt radio bursts.

Abstract

We discuss observational strategies to detect prompt bursts associated with gravitational wave events using the Australian Square Kilometre Array Pathfinder (ASKAP). Many theoretical models of binary neutron stars mergers predict that bright, prompt radio emission would accompany the merger. The detection of such prompt emission would greatly improve our knowledge of the physical conditions, environment, and location of the merger. However, searches for prompt emission are complicated by the relatively poor localisation for gravitational wave events, with the 90\% credible region reaching hundreds or even thousands of square degrees. Operating in fly's eye mode, the ASKAP field of view can reach $\sim$1000 deg$^2$ at $\sim 888\,{\rm MHz}$. This potentially allows observers to cover most of the 90\% credible region quickly enough to detect prompt emission. We use skymaps for GW170817 and GW190814 from LIGO/Virgo's third observing run to simulate the probability of detecting prompt emission for gravitational wave events in the upcoming fourth observing run. With only alerts released after merger we find it difficult to slew the telescope sufficiently quickly as to capture any prompt emission. However, with the addition of alerts released \textit{before} merger by negative-latency pipelines we find that it should be possible to search for nearby, bright prompt FRB-like emission from gravitational wave events. Nonetheless, the rates are low: we would expect to observe $\sim$0.012 events during the fourth observing run, assuming that the prompt emission is emitted microseconds around the merger