Spectral constraints on the redshift of the optical counterpart to the γ-ray burst of 8 May 1997
Spectral constraints on the redshift of the optical counterpart to the γ-ray burst of 8 May 1997
复制标题
DOI：
10.1038/43132
复制
发表时间：
1997-06
期刊：
影响因子：
64.8
通讯作者：
M. Metzger;S. Djorgovski;S. Kulkarni;C. Steidel;K. Adelberger;D. Frail;E. Costa;F. Frontera
中科院分区：
文献类型：
--
作者：
M. Metzger;S. Djorgovski;S. Kulkarni;C. Steidel;K. Adelberger;D. Frail;E. Costa;F. Frontera
短暂而强烈的γ射线爆发几乎每天都从太空中的随机方向发生，但自25年前首次发现以来，它们的起源一直未知。基于观测到的各向同性和视亮度分布的参数不足以将爆发的位置限制在局部或宇宙学起源上。因此，最近在其他波长上探测到的γ射线爆发的对应物，增加了这些高能事件的来源可能很快被揭示的希望。在这里，我们报告光谱观测的可能光学对应的γ射线暴GRB 970508。除了几条显著的吸收线外，光谱基本上没有什么特征，我们把这几条吸收线归因于沿视线沿着在红移= 0.835处的吸收系统的存在。再加上光谱中没有莱曼-α森林特征，我们的结果意味着光学瞬态位于0.835 μ z ~ 2.3。如果光学瞬变确实是GRB 970508的对应物，我们的结果提供了第一个直接限制到γ射线爆发的距离，证实至少有一些事件位于宇宙学距离，因此是高能量的。
Brief, intense bursts of γ-rays occur approximately daily from random directions in space, but their origin has remained unknown since their initial detection almost 25 years ago. Arguments based on their observed isotropy and apparent brightness distribution are not sufficient to constrain the location of the bursts to a local or cosmological origin. The recent detection of a counterpart to a γ-ray burst at other wavelengths, has therefore raised the hope that the sources of these energetic events might soon be revealed. Here we report spectroscopic observations of the possible optical counterpart, to the γ-ray burst GRB970508. The spectrum is mostly featureless, except for a few prominent absorption lines which we attribute to the presence of an absorption system along the line of sight at redshiftz= 0.835. Coupled with the absence of Lyman-α forest features in the spectra, our results imply that the optical transient lies at 0.835 ⩽z≲ 2.3. If the optical transient is indeed the counterpart of GRB970508, our results provide the first direct limits on the distance to a γ-ray burst, confirming that at least some of these events lie at cosmological distances, and are thus highly energetic.