Panaitescu 2007 Swift X射线的喷流拐折

主要内容:
分析了236（有的没有X射线余辉）个Swift暴的晚期X射线拐折，形态各异。60%有“好的”拐折。Swift之前有75%有“好的”光学怪折的。比例差不多。

精彩摘抄:


文章信息:
Jet-breaks in the X-ray Light-Curves of Swift GRB Afterglows

Authors: A. Panaitescu

(Submitted on 8 May 2007)

Abstract: In the set of 236 GRB afterglows observed by Swift between January 2005 and March 2007, we identify 30 X-ray light-curves whose power-law fall-off exhibit a steepening ("break") at 0.1-10 day after trigger, to a decay steeper than t^{-1.5}. For most of these afterglows, the X-ray spectral slope and the decay indices before and after the break can be accommodated by the standard jet model although a different origin of the breaks cannot be ruled out. In addition, there are 27 other afterglows whose X-ray light-curves may also exhibit a late break to a steep decay, but the evidence is not that compelling.
The X-ray emissions of 38 afterglows decay slower than t^{-1.5} until after 3 day, half of them exhibiting such a slow decay until after 10 day.
Therefore, the fraction of well-monitored Swift afterglows with potential jet-breaks is around 60 percent, whether we count only the strongest cases for each type or all of them. This fraction is comparable to the 75 percent of pre-Swift afterglows whose optical light-curves displayed similar breaks at ~1 day.
The properties of the prompt emission of Swift afterglows with light-curve breaks show the same correlations (peak energy of GRB spectrum with the burst isotropic output and with burst collimated output) as previously found for pre-Swift optical afterglows with light-curve breaks (the Amati and Ghirlanda relations, respectively). However, we find that Ghirlanda relation is largely a consequence of Amati's and that the addition of a new observable (the jet-break time) leads to a stronger correlation only when the few outliers to the Amati relation are taken into account.

Comments:

7 pages, submitted to MNRAS

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.1015v1 [astro-ph]