A comprehensive search for the radio counterpart of GW190814 with the Australian Square Kilometre Array Pathfinder

TL;DR

This study conducted an extensive radio search for the electromagnetic counterpart of GW190814 using ASKAP, covering most of the event's localization area over multiple epochs, and set constraints on the merger's environment and inclination.

Contribution

It is the most comprehensive widefield radio transient search for GW counterparts to date, providing valuable constraints and a detailed survey methodology.

Findings

Detected one radio transient unlikely linked to GW190814

Placed constraints on the merger's inclination angle

Set limits on the surrounding environment density

Abstract

We present results from a search for the radio counterpart to the possible neutron star-black hole merger GW190814 with the Australian Square Kilometre Array Pathfinder. We have carried out 10 epochs of observation spanning 2-655 days post-merger at a frequency of 944 MHz. Each observation covered 30 deg$^2$, equivalent to 87% of the event localisation. We conducted an untargeted search for radio transients in the field, as well as a targeted search for transients associated with known galaxies. We find one radio transient, ASKAP J005022.3-230349, but conclude that it is unlikely to be associated with the merger. We use our observations to place constraints on the inclination angle of the merger and the density of the surrounding environment by comparing our non-detection to model predictions for radio emission from compact binary coalescences. This survey is also the most comprehensive widefield search (in terms of sensitivity and both areal and temporal coverage) for radio transients to-date and we calculate the radio transient surface density at 944 MHz.