Strategies for Finding Prompt Radio Counterparts to Gravitational Wave Transients with the Murchison Widefield Array

TL;DR

This paper explores strategies using the Murchison Widefield Array to detect prompt low-frequency radio signals associated with gravitational wave events, aiming to improve detection coverage and constrain emission models.

Contribution

It introduces and evaluates observational strategies for detecting prompt radio counterparts to gravitational wave transients with the MWA, considering field-of-view and pointing limitations.

Findings

MWA can cover >50% of GW error regions for some events.

Detection sensitivity can reach 0.1 Jy for 10-s transients.

Constraints on prompt emission models can be achieved with current capabilities.

Abstract

We present and evaluate several strategies to search for prompt, low-frequency radio emission associated with gravitational wave transients using the Murchison Widefield Array (MWA). As we are able to repoint the MWA on timescales of tens of seconds, we can search for the dispersed radio signal that has been predicted to originate along with or shortly after a neutron star-neutron star merger. We find that given the large, 600 deg^2 instantaneous field-of-view of the MWA we can cover a significant fraction of the predicted gravitational wave error region, although due to the complicated geometry of the latter we only cover >50% of the error region for approximately 5% of events, and roughly 15% of events will be located <10 deg from the MWA pointing center such that they will be covered in the radio images. For optimal conditions our limiting flux density for a 10-s long transient would be 0.1 Jy, increasing to about 1 Jy for a wider range of events. This corresponds to luminosity limits of 1e38-1e39 erg/s based on expectations for the distances of the gravitational wave transients, which should be sufficient to detect or significantly constrain a range of models for prompt emission.