van Marle 2006 长暴的暴周环境 4

主要内容:
也说是ISM和wind，给了个新名词：暴周环境的简写－CSM。指出在余辉的谱上有蓝移的现象（这种谱应该是CSM的吸收导致），说明CSM在远离中心源，就应该是wind了。

精彩摘抄:


文章信息:

astro-ph/0611812 [abs, ps, pdf, other] :

Title: Models for the circumstellar medium of long gamma-ray burst progenitor candidates
Authors: A.J. van Marle, N. Langer, A. Achterberg, G. Garcia-Segura
Comments: To appear in the proceedings of: "Circumstellar Media and Late Stages of Massive Stellar Evolution", September 4-8, 2006, Ensenada, Baja California, Mexico

We present hydrodynamical models of circumstellar medium (CSM) of long gamma-ray burst (GRB) progenitor candidates. These are massive stars that have lost a large amount of mass in the form of stellar wind during their evolution.
There are two possible ways to probe the CSM of long GRB progenitors. Firstly, the GRB afterglow consists of synchrotron radiation, emitted when the GRB jet sweeps up the surrounding medium. Therefore, the lightcurve is directly related to the density profile of the CSM. The density can either decrease with the radius squared (as is the case for a freely expanding stellar wind) or be constant (as we would expect for shocked wind or the interstellar medium). Secondly, material between the GRB and the observer will absorb part of the afterglow radiation, causing absorption lines in the afterglow spectrum. In some cases, such absorption lines are blue-shifted relative to the source indicating that the material is moving away from the progenitor star. This can be explained in terms of wind interactions in the CSM. We can use the CSM of these stars to investigate their prior evolutionary stage.