Short Gamma Ray Bursts: a bimodal origin?

TL;DR

This paper investigates the origins of short gamma-ray bursts, showing that both field and globular cluster formation channels are necessary to explain observed distributions, with different channels dominating at different redshifts.

Contribution

It provides a combined analysis of field and globular cluster channels for SGRB origins, fitting flux distributions and comparing with observational data to identify their relative contributions.

Findings

Globular cluster channels dominate at z<0.3

Field binary channels explain high-z SGRBs

Both channels are necessary to match observations

Abstract

Short-hard Gamma Ray Bursts (SGRBs) are currently thought to arise from gravitational wave driven coalescences of double neutron star systems forming either in the field or dynamically in globular clusters. For both channels we fit the peak flux distribution of BATSE SGRBs to derive the local burst formation rate and luminosity function. We then compare the resulting redshift distribution with Swift 2-year data, showing that both formation channels are needed in order to reproduce the observations. Double neutron stars forming in globular clusters are found to dominate the distribution at z<0.3, whereas the field population from primordial binaries can account for the high-z SGRBs. This result is not in contradiction with the observed host galaxy type of SGRBs.