A SIZE-DURATION TREND FOR GAMMA-RAY BURST PROGENITORS

Anna Barnacka,Abraham Loeb

doi:10.1088/2041-8205/794/1/l8

Anna Barnacka, Abraham Loeb

Open Access

https://doi.org/10.1088/2041-8205/794/1/l8

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Abstract

Gamma-ray bursts (GRBs) show a bimodal distribution of durations, separated at a duration of ~2 s. Observations have confirmed the association of long GRBs with the collapse of massive stars. The origin of short GRBs is still being explored. We examine constraints on the emission region size in short and long GRBs detected by Fermi/GBM. We find that the emission region size during the prompt emission, R, and the burst duration, T$_{90}$, are consistent with the relation R ~ c x T$_{90}$, for both long and short GRBs. We find the characteristic size for the prompt emission region to be ~2 x 10$^{10}$ cm, and ~4 x 10$^{11}$ cm for short and long GRBs, respectively.

Highlights

The first catalog of gamma-ray bursts (GRBs) detected by the BATSE satellite revealed bimodality in their duration distribution (Kouveliotou et al 1993)
Events lasting longer than 2 s were classified as long GRBs, while those shorter than 2 s were classified as short GRBs
The discovery of optical afterglows following some of the long GRBs detected by BeppoSAX and environmental studies indicated that long GRBs originate in star-forming galaxies (Bloom et al 1998; Djorgovski et al 1998) and their location is spatially correlated with star-forming regions within their hosts (Fruchter et al 2006)

Summary

Introduction

The first catalog of gamma-ray bursts (GRBs) detected by the BATSE satellite revealed bimodality in their duration distribution (Kouveliotou et al 1993). The discovery of optical afterglows following some of the long GRBs detected by BeppoSAX (van Paradijs et al 1997; Metzger et al 1997) and environmental studies indicated that long GRBs originate in star-forming galaxies (Bloom et al 1998; Djorgovski et al 1998) and their location is spatially correlated with star-forming regions within their hosts (Fruchter et al 2006). Some of the long GRBs are associated with Type Ic supernovae (Hjorth et al 2003; Stanek et al 2003). These clues indicate that long GRBs are associated with the core collapse of massive stars (collapsars), and not with the merger of compact object binaries (Paczynski 1998; MacFadyen & Woosley 1999)

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Discussion

Conclusion