An Unexpectedly Swift Rise in the Gamma-ray Burst Rate
Abstract
The association of long gamma-ray bursts with supernovae naturally suggests that the cosmic GRB rate should trace the star formation history. Finding otherwise would provide important clues concerning these rare, curious phenomena. Using a new estimate of Swift GRB energetics to construct a sample of 36 luminous GRBs with redshifts in the range z=0-4, we find evidence of enhanced evolution in the GRB rate, with ~4 times as many GRBs observed at z~4 than expected from star formation measurements. This direct and empirical demonstration of needed additional evolution is a new result. It is consistent with theoretical expectations from metallicity effects, but other causes remain possible, and we consider them systematically.
Cite
@article{arxiv.0709.0381,
title = {An Unexpectedly Swift Rise in the Gamma-ray Burst Rate},
author = {Matthew D. Kistler and Hasan Yuksel and John F. Beacom and Krzysztof Z. Stanek},
journal= {arXiv preprint arXiv:0709.0381},
year = {2010}
}
Comments
4 pages, 4 figures; minor changes to agree with published version