EDP Sciences
Free access
Issue
A&A
Volume 435, Number 2, May IV 2005
Page(s) 421 - 426
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20041702


A&A 435, 421-426 (2005)
DOI: 10.1051/0004-6361:20041702

The luminosity and redshift distributions of short-duration GRBs

D. Guetta1, 2 and T. Piran2

1  Osservatorio astronomico di Roma, v. Frascati 33, 00040 Monte Porzio Catone, Italy
    e-mail: dafne@arcetri.astro.it
2  Racah Institute for Physics, The Hebrew University, Jerusalem 91904, Israel
    e-mail: tsvi@tapir.caltech.edu

(Received 21 July 2004 / Accepted 22 December 2004)

Abstract
Using the BATSE peak flux distribution we rederive the short GRBs luminosity function and compare it with the observed redshift distribution of long bursts. We show that both distributions are compatible with the assumption that short as well as long bursts follow the star formation rate. In this case the difference between the two observed distributions can be interpreted as arising mostly from differences in the detector's sensitivity to long and short bursts, while the local rate of short bursts is 0.1 h703 Gpc-3 yr-1. We also consider the possibility that short GRBs may be associated with binary neutron star mergers and estimate the effect of the merging time delay on the luminosity function and redshift distribution. We find that in this case the local rate of short GRBs is ~ 0.8 h703 Gpc-3 yr-1. Assuming that all binary merging systems lead to short GRBs, we find a typical jet opening angle of $1.6^\circ$.


Key words: cosmology: observations -- gamma rays: bursts

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