Precursors of short gamma-ray bursts

TL;DR

This study systematically searches for precursor emissions in short gamma-ray bursts observed by Swift, finding that about 8-10% exhibit precursors, with implications for understanding merger mechanisms and quantum gravity constraints.

Contribution

First systematic analysis of precursors in short GRBs observed by Swift, revealing their occurrence rate and characteristics.

Findings

8-10% of short GRBs have precursors

One GRB shows two precursor events before the main burst

No significant difference between precursor and main emission

Abstract

We carried out a systematic search of precursors on the sample of short GRBs observed by Swift. We found that ~8-10% of short GRBs display such early episode of emission. One burst (GRB 090510) shows two precursor events, the former ~13 s and the latter ~0.5 s before the GRB. We did not find any substantial difference between the precursor and the main GRB emission, and between short GRBs with and without precursors. We discuss possible mechanisms to reproduce the observed precursor emission within the scenario of compact object mergers. The implications of our results on quantum gravity constraints are also discussed.