Radio precursors to neutron star binary mergings

TL;DR

This paper explores the potential for detecting radio bursts that precede neutron star mergers, which could be identified using low-frequency radio telescopes like LOFAR, aiding early detection of such cosmic events.

Contribution

It proposes a model for radio precursors to neutron star mergers, estimates detection rates with LOFAR, and highlights the importance of the radio emission mechanism's efficiency.

Findings

LOFAR could detect several neutron star merger precursors per month.

Radio signals may be delayed by 10 to hundreds of seconds, allowing pre-merger alerts.

Detection depends critically on the efficiency of low-frequency radio emission mechanisms.

Abstract

We discuss a possible generation of radio bursts preceding final stages of binary neutron star mergings which can be accompanied by short gamma-ray bursts. Detection of such bursts appear to be advantageous in the low-frequency radio band due to a time delay of ten to several hundred seconds required for radio signal to propagate in the ionized intergalactic medium. This delay makes it possible to use short gamma-ray burst alerts to promptly monitor specific regions on the sky by low-frequency radio facilities, especially by LOFAR. To estimate the strength of the radio signal, we assume a power-law dependence of the radio luminosity on the total energy release in a magnetically dominated outflow, as found in millisecond pulsars. Based on the planned LOFAR sensitivity at 120 MHz, we estimate that the LOFAR detection rate of such radio transients could be about several events per month from redshifts up to $z\sim1.3$ in the most optimistic scenario. The LOFAR ability to detect such events would crucially depend on exact efficiency of low-frequency radio emission mechanism.