Prospects for joint observations of gravitational waves and gamma rays from merging neutron star binaries

TL;DR

This paper evaluates the prospects for detecting joint gravitational wave and gamma-ray signals from neutron star mergers, using simulations to predict detection rates and inform understanding of short gamma-ray burst origins.

Contribution

It introduces a Monte Carlo simulation pipeline to estimate joint GW and gamma-ray detection rates for neutron star mergers with current and future detector sensitivities.

Findings

Detection rate is low during 2016-2017 but increases tenfold with improved sensitivities.

Future joint observations can clarify the link between short GRBs and neutron star mergers.

Comparison of observed and predicted rates constrains GRB jet geometry.

Abstract

The detection of the events GW150914 and GW151226, both consistent with the merger of a binary black hole system (BBH), opened the era of gravitational wave (GW) astronomy. Besides BBHs, the most promising GW sources are the coalescences of binary systems formed by two neutron stars or a neutron star and a black hole. These mergers are thought to be connected with short Gamma Ray Bursts (GRBs), therefore combined observations of GW and electromagnetic (EM) signals could definitively probe this association. We present a detailed study on the expectations for joint GW and high-energy EM observations of coalescences of binary systems of neutron stars with Advanced Virgo and LIGO and with the \emph{Fermi} gamma-ray telescope. To this scope, we designed a dedicated Montecarlo simulation pipeline for the multimessenger emission and detection by GW and gamma-ray instruments, considering the evolution of the GW detector sensitivities. We show that the expected rate of joint detection is low during the Advanced Virgo and Advanced LIGO 2016-2017 run; however, as the interferometers approach their final design sensitivities, the rate will increase by $\sim$ a factor of ten. Future joint observations will help to constrain the association between short GRBs and binary systems and to solve the puzzle of the progenitors of GWs. Comparison of the joint detection rate with the ones predicted in this paper will help to constrain the geometry of the GRB jet.