伽玛暴(Gamma-Ray Burst)笔记。记录有关伽玛暴的新文章,另外也包括看的老文章、自己的想法、以及跟天文相关的一些东西。 Feel free to leave me a message by comments or by email.

星期三, 五月 12, 2010

Holland 2010 暗暴GRB 090417B和它的宿主星系

主要内容:
又一个说暗暴可能是来自于宿主星系的尘埃消光的。这个的A_V>12mag


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文章信息:
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· arXiv e-print (arXiv:1005.1675)
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Title:
GRB 090417B and its Host Galaxy: A Step Towards an Understanding of Optically-Dark Gamma-Ray Bursts
Authors:
Holland, Stephen T.; Sbarufatti, Boris; Shen, Rongfeng; Schady, Patricia; Cummings, Jay R.; Fonseca, Emmanuel;Fynbo, Johan P. U.; Jakobsson, Pall; Leitet, Elisabet; Linne, Staffan; Roming, Peter W. A.; Still, Martin; Zhang, Bing
Publication:
eprint arXiv:1005.1675
Publication Date:
05/2010
Origin:
ARXIV
Keywords:
Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:
Accepted for publication in ApJ
Bibliographic Code:
2010arXiv1005.1675H

Abstract

GRB 090417B was an unusually long burst with a T_90 duration of at least 2130 s and a multi-peaked light curve at energies of 15-150 keV. It was optically dark and has been associated with a bright star-forming galaxy at a redshift of 0.345 that is broadly similar to the Milky Way. This is one of the few cases where a host galaxy has been clearly identified for a dark gamma-ray burst and thus an ideal candidate for studying the origin of dark bursts. We find that the dark nature of GRB 090417B cannot be explained by high redshift, incomplete observations, or unusual physics in the production of the afterglow. Assuming the standard relativistic fireball model for the afterglow we find that the optical flux is at least 2.5 mag fainter than predicted by the X-ray flux. The Swift/XRT X -ray data are consistent with the afterglow being obscured by a dense, localized sheet of dust approximately 30-80 pc from the burst along the line of sight. Our results suggest that this dust sheet imparts an extinction of A_V >~ 12 mag, which is sufficient to explain the missing optical flux. GRB 090417B is an example of a gamma-ray burst that is dark due to the localized dust structure in its host galaxy.
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