Chen Hsiao-Wen
Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637, USA.
Philos Trans A Math Phys Eng Sci. 2007 May 15;365(1854):1247-53. doi: 10.1098/rsta.2006.1972.
A systematic search of Wolf-Rayet wind signatures, as represented by blue-shifted, high-velocity (|Deltav|=1000-5000 kms(-1)) C IV lambdalambda 1548, 1550 absorption doublet has yielded an estimate of 20% for the incidence of these C IV absorbers near the host galaxies of gamma-ray bursts (GRBs). This is consistent with what is observed near classical damped Lyalpha absorbers that have a comparable neutral hydrogen column density as the GRB host galaxies. A detailed ionization analysis of these absorbers, including the associated low-ionization species, shows that the majority in fact originate in foreground galaxies along the sightline, rather than in the vicinity of the GRB afterglows. Taking into account the enhanced afterglow radiation field, the lack of Wolf-Rayet signatures can be applied to constrain the C/He ratio and the density contrast of the winds in the vicinity of GRB progenitor stars.
对沃尔夫-拉叶星风特征进行系统搜索，以蓝移、高速（|Δv| = 1000 - 5000 km s⁻¹）的C IV λλ1548、1550吸收双线表示，结果表明在伽马射线暴（GRB）宿主星系附近这些C IV吸收体的发生率估计为20%。这与在具有与GRB宿主星系相当的中性氢柱密度的经典阻尼莱曼α吸收体附近所观测到的情况一致。对这些吸收体进行详细的电离分析，包括相关的低电离物种，结果表明实际上大多数起源于视线方向上的前景星系，而非GRB余辉附近。考虑到增强的余辉辐射场，沃尔夫-拉叶星特征的缺失可用于约束GRB前身星附近风的C/He比和密度对比度。
