Nysewander 2008 长暴和短暴余辉的比较

主要内容:
发现短暴的暴周应该是星风环境，而且致密程度甚至超过长暴。说明可能标准模型有误。

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文章信息:

· arXiv e-print (arXiv:0806.3607)

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Title:		A Comparison of the Afterglows of Short- and Long-Duration Gamma-Ray Bursts
Authors:		Nysewander, M.; Fruchter, A. S.; Pe'er, A.
Publication:		eprint arXiv:0806.3607
Publication Date:		06/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		main: 37 pages, 7 figures, 4 tables; online table: 63 pages; submitted to ApJ
Bibliographic Code:		2008arXiv0806.3607N

Abstract

We present a comparative study of the observed properties of the optical and X-ray afterglows of short- and long-duration $\gamma$-ray bursts (GRBs). Using a large sample of 37 short GRBs and 421 long GRBs, we find a strong correlation between afterglow brightness measured after 11 hours and the energy release in the prompt emission, measured in both the optical (R band) and X-ray flux and E$_{ISO}$ : $F_{R,X} \propto {E_{ISO}}^{\alpha}$, with $\alpha \simeq 1$ in both cases. Furthermore, the constant of proportionality is nearly identical for long and short bursts. Therefore, for a given fluence, the afterglows of short GRBs are not significantly dimmer than those of long GRBs in the optical and the X-ray bands. This result is difficult to explain in the framework of the standard scenario, since it requires that either (1) the average number density of the surrounding medium of short bursts is comparable to, or even larger than the number density of long bursts; or (2) short bursts explode into a density profile, $n(r) \propto r^{-2}$. We therefore find it likely that either basic assumptions on the properties of the circumburst environment of short GRBs, and thus the merger origin theory of short bursts, are incorrect, or else the standard models of GRB emission must be fully re-examined.

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