Kocevski 2007 Swift暴的能量

主要内容:
统计了76个有红移的Swift暴的辐射能量，把它们和 红移、光变指数、t_jet等放在一起统计。

精彩摘抄:
暴的能量和红移的统计图，居然有这个趋势？

文章信息:

arXiv:0707.4478 [ps, pdf, other]

Title: GRB Energetics in the Swift Era

Authors: Daniel Kocevski, Nathaniel Butler

Comments: 30 pages, 10 figures, Submitted to ApJ

Subjects: Astrophysics (astro-ph)

We examine the rest frame energetics of 76 gamma-ray bursts (GRBs) with known redshift that were detected by the Swift spacecraft. Using the bolometric fluence values estimated in \citet{Butler07b} and the last XRT observation for each event, we set a lower limit the their collimation corrected energy $E_{\gamma}$ and find that a 68% of our sample are at high enough redshift and/or low enough fluence to accommodate a jet break occurring beyond the last XRT observation and still be consistent with the pre-Swift $E_{\gamma}$ distribution for long GRBs. We find that relatively few of the X-ray light curves for the remaining events show evidence for late-time decay slopes that are consistent with that expected from post jet break emission. The breaks in the X-ray light curves that do exist tend to be shallower and occur earlier than the breaks previously observed in optical light curves, yielding a $E_{\gamma}$ distribution that is far lower than the pre-Swift distribution. If these early X-ray breaks are not due to jet effects, then a small but significant fraction of our sample have lower limits to their collimation corrected energy that place them well above the pre-Swift $E_{\gamma}$ distribution. Either scenario would necessitate a much wider post-Swift $E_{\gamma}$ distribution for long cosmological GRBs compared to the narrow standard energy deduced from pre-Swift observations.