Last moments in the life of a compact binary system: gravitational waves, gamma-ray bursts and magnetar formation

TL;DR

This paper reviews the observable signatures of compact binary mergers, including gravitational waves, gamma-ray bursts, and magnetar formation, highlighting their roles in short GRB phenomena and late-time X-ray activity.

Contribution

It provides a comprehensive overview of expected signals and mechanisms from neutron star mergers, integrating gravitational, electromagnetic, and neutrino observations.

Findings

Neutron star mergers produce distinct gravitational wave signatures.

Neutrino-cooled accretion disks influence gamma-ray burst mechanisms.

Magnetar formation may occur in some neutron star mergers.

Abstract

The first detections of afterglows from short gamma-ray bursts (GRBs) have confirmed the previous suspicion that they are triggered by a different central engine than long bursts. In particular, the recent detections of short GRBs in galaxies without star formation lends support to the idea that an old stellar population is involved. Most prominent are mergers of either double neutron stars or of a neutron star with a stellar-mass black hole companion. Since the final identification of the central engine will only come from an integral view of several properties, we review the observable signatures that can be expected from both double neutron stars and neutron star black hole systems. We discuss the gravitational wave emission, the structure of the neutrino-cooled accretion disks, the resulting neutrino signal and possible mechanisms to launch a GRB. In addition, we address the speculative idea that in some cases a magnetar-like object may be the final outcome of a double neutron star merger. We also discuss possibilities to explain the late-time X-ray activity that has been observed in several bursts.