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arXiv · 0709.0381

An Unexpectedly Swift Rise in the Gamma-ray Burst Rate

Matthew D. Kistler·Hasan Yuksel·John F. Beacom·Krzysztof Z. Stanek
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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.

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Matthew D. Kistler, Hasan Yuksel, John F. Beacom, Krzysztof Z. Stanek. 2008-07-01. An Unexpectedly Swift Rise in the Gamma-ray Burst Rate. https://doi.org/10.1086/527671

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