Soft X-ray spectrum of BL Lacertae object AO 0235+164 as a tracer of elemental abundances at z approximately 0.5
Soft X-ray spectrum of BL Lacertae object AO 0235+164 as a tracer of elemental abundances at z approximately 0.5
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BL Lacertae 物体 AO 0235 164 的软 X 射线光谱作为 z 约 0.5 处元素丰度的示踪剂
DOI：
10.1086/174593
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
G. Madejski
中科院分区：
文献类型：
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作者：
G. Madejski
本文报道了用爱因斯坦天文台成像正比计数器（IPC）观测到的BL Lac天体AO 0235+164的软X射线谱。这个物体（z = 0.94）有一个在z = 0.524的介入星系（或原星系盘）存在于视线中，在背景BL Lac连续谱中产生射电和光学吸收线。X射线光谱显示出相当大的软X射线截止，相当于我们银河系预期的几倍;我们解释说，多余的截止是由于干预星系。从21厘米射电数据和X射线吸收推断的氢柱密度的比较允许，在原则上，在干预星系的元素丰度的确定。然而，H I自旋温度和X射线光谱参数的不确定性只是松散地限制这些丰度为2 +/- 1太阳，即使在下限似乎高于从光学吸收线系统的样品的研究推断。
We report the soft X-ray spectrum of BL Lac object AO 0235+164, observed with the Einstein Observatory Imaging Proportional Counter (IPC). This object (z = 0.94) has an intervening galaxy (or a protogalactic disk) at z = 0.524 present in the line of sight, producing both radio and optical absorption lines in the background BL Lac continuum. The X-ray spectrum exhibits a substantial soft X-ray cutoff, corresponding to several times that expected from our own Galaxy; we interpret that excess cutoff as due to the intervening galaxy. The comparison of the hydrogen column density inferred from the 21 cm radio data and the X-ray absorption allows, in principle, the determination of the elemental abundances in the intervening galaxy. However, the uncertainties in both the H I spin temperature and X-ray spectral parameters only loosely restrict these abundances to be 2 +/- 1 solar, which even at the lower limit appears higher than that inferred from studies of samples of optical absoprtion-line systems.