Implications For The Origin Of GRB 051103 From LIGO Observations

TL;DR

This study used LIGO data to search for gravitational waves from GRB 051103, a short gamma-ray burst near galaxy M81, and found no evidence, which supports the hypothesis that it was caused by an SGR giant flare rather than a merger.

Contribution

First LIGO search for gravitational waves associated with GRB 051103, providing constraints on its progenitor and supporting the SGR giant flare hypothesis.

Findings

Excluded binary neutron star merger in M81 with 98% confidence

Excluded neutron star-black hole merger with >99% confidence

Supported the SGR giant flare origin hypothesis for GRB 051103

Abstract

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at the distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with > 99% confidence. If the event occurred in M81 our findings support the the hypothesis that GRB 051103 was due to an SGR giant flare, making it the most distant extragalactic magnetar observed to date.