Year: 2009
Type: article
Abstract: The gamma-ray burst (GRB) mission Swift has made a much deeper GRB survey than any previous one. I present a systematical comparison between GRB samples detected with pre- Swift missions and those from Swift , in order to investigate whether they show any statistical difference. Our Swift GRB sample includes the bursts detected by Swift /BAT before 2007 September. With both flux-limited surveys and redshift-known GRB samples, I show that, apparently, the observed distributions of the redshifts, T 90 , and log N – log P are significantly different, but not for the spectral hardness ratio, fluence and E iso . The redshifts of the Swift GRB sample are statistically larger than those of pre- Swift GRBs, with a mean of 1.95±0.17 compared to ∼ 1 for pre- Swift GRBs. The cosmological effect on the observables is thus considerable. This effect on the spectral hardness ratio, fluence and E iso is cancelled out, and the distributions of these quantities indeed do not show significant differences between the Swift and pre- Swift GRBs. Taking this effect into account, I found that the corrected distributions of T 90 for long GRBs and log N – log P observed with Swift /BAT are also consistent with those observed with CGRO/BATSE. These results indicate that the Swift and pre- Swift GRBs are from the same population.
Author: Yi-Qing Lin
Institution: Xiamen University of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2112890581