Electromagnetic Counterparts of Gravitational Wave Sources : Mergers of Compact Objects

TL;DR

This paper explores electromagnetic signatures of compact object mergers, especially black hole mergers, highlighting their potential as detectable radio transients and discussing how to distinguish them from supernovae.

Contribution

It presents the possibility that black hole mergers produce luminous radio transients and discusses methods to identify these events among other astrophysical phenomena.

Findings

BH-BH mergers can produce luminosities exceeding Eddington limits.

Radio transients from mergers could be detectable up to 300 Mpc.

These transients may resemble radio supernovae but can be distinguished through multi-band observations.

Abstract

Mergers of compact objects are considered prime sources of gravitational waves (GW) and will soon be targets of GW observatories such as the Advanced-LIGO, VIRGO etc. Finding electromagnetic counterparts of these GW sources will be important to understand their nature. We discuss possible electromagnetic signatures of the mergers. We show that the BH-BH mergers could have luminosities which exceed Eddington luminosity from unity to several orders of magnitude depending on the masses of the merging BHs. As a result these mergers could be explosive, release up to $10^{51}$ erg of energy and shine as radio transients. At any given time we expect about a few such transients in the sky at GHz frequencies which could be detected out to about 300 Mpc. It has also been argued that these radio transients would look alike radio supernovae with comparable detection rates. Multi-band follow up could, however, distinguish between the mergers and supernovae.