The Smoking Guns Of Neutron Stars Mergers

TL;DR

This paper discusses how neutron star mergers produce observable gamma-ray bursts and associated isotropic afterglows, providing a universal signature that can be detected regardless of beaming effects or visibility from Earth.

Contribution

It introduces the concept of a universal isotropic afterglow as a smoking gun for neutron star mergers, independent of gamma-ray burst beaming and visibility.

Findings

Neutron star mergers produce beamed short gamma-ray bursts.

Pulsar wind nebula creates an isotropic early-time afterglow.

This afterglow serves as a universal signature of neutron star mergers.

Abstract

The short hard gamma ray burst (SHB) 170817A that followed GW170817A, the first neutron stars merger (NSM) detected in gravitational waves (GWs), has shown beyond doubt that NSMs produce beamed SHBs. Its low luminosity and other properties that differ from those of ordinary SHBs were predicted by the cannonball model of gamma ray bursts. Low luminosity (LL) SHBs are mainly ordinary SHBs viewed far off-axis. They are produced mainly by nearby NSMs. Because of beaming, most of the NSMs, including those within the current horizon of Ligo-Virgo, produce SHBs most of which are invisible from Earth. But, their pulsar wind nebula powered by the spin down of the remnant neutron star produces an early-time isotropic afterglow with a universal temporal shape. This smoking gun of NSMs is detectable independent of whether the SHB was visible, or was invisible from Earth because of being beamed away.