On the Origin of the Highest Redshift Gamma-ray Bursts

Content Provider	Semantic Scholar
Author	Belczýnski, Krzysztof Holz, Daniel E. Fryer, Chris L. Berger, E. T. Hartmann, D. H. Shea, Brian J. O’
Copyright Year	2009
Abstract	GRB 080913 and GRB 090423 are the most distant gamma-ray bursts (GRBs) known to-date, with spectroscopically determined redshifts of z = 6.7 and z = 8.1, respectively. The detection of bursts at this early epoch of the Universe significantly constrains the nature of GRBs and their progenitors. We perform population synthesis studies of the formation and evolution of early stars, and calculate the resulting formation rates of short and long-duration GRBs at high redshift. The peak of the GRB rate from Population II stars occurs at z ∼ 7 for a model with efficient/fast mixing of metals, while it is found at z ∼ 3 for an inefficient/slow metallicity evolution model. We show that in the redshift range 6 ∼< z ∼< 10 essentially all GRBs originate from Population II stars, regardless of metallicity evolution model. These stars (having small, but non-zero metallicity) are the most likely progenitors for both long GRBs (collapsars) and short GRBs (NS-NS or BH-NS mergers) at this epoch. Although the predicted intrinsic rates of long and short GRBs are similar at these high redshifts, observational selection effects lead to higher (factor of ∼ 10) observed rates for long GRBs. We conclude that the two recently observed high-z GRB events are most likely long GRBs originating from Population II collapsars. Subject headings: binaries: general—gamma rays: bursts—stars: formation
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://arxiv.org/pdf/0812.2470v2.pdf
Language	English
Access Restriction	Open
Subject Keyword	Arabic numeral 0 GZMB wt Allele Gamma correction Interferon Type II Medical Subject Headings Metals Population dynamics Rajiformes Redshift Selection bias Stars, Celestial X86
Content Type	Text
Resource Type	Article