H I 21 Centimeter Absorption in Two Low-Redshift Damped Lyα Systems
H I 21 Centimeter Absorption in Two Low-Redshift Damped Lyα Systems
复制标题
两个低红移阻尼 Lyα 系统中的 H I 21 厘米吸收
DOI：
10.1086/300422
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
G. Meylan
中科院分区：
文献类型：
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作者：
W. Lane;A. Smette;A. Smette;F. Briggs;S. Rao;D. Turnshek;G. Meylan
我们报告发现了两个低红移的H I 21 cm吸收体，一个位于z = 0.2212，朝向zem = 0.630的类星体OI 363 (B0738+313)，另一个位于z = 0.3127，朝向PKS B1127-145 （zem = 1.187）。这两个都是在使用Westerbork合成射电望远镜的新UHF-high系统对Mg ii选择的系统进行红移0.2 < z < 1的调查时发现的。新的哈勃太空望远镜微弱天体摄谱仪观测也确定这两个系统都是阻尼Lyα (DLA)吸收体。通过比较DLA线和hi - 21cm线的柱密度，我们计算了两种体系的自旋温度Ts。我们发现这两种低红移吸收剂的Ts≈1000k。对于朝向PKS B1127-145的z = 0.3127系统，Bergeron & boiss<s:1>先前已经在吸收红移处发现了两个星系的发射线，其中距离类星体较近的星系被认为是吸收系统的原因。ESO新技术望远镜/EFOSC2拍摄的第三颗较暗的伴星的光谱。″9，或11 h kpc，从PKS B1127-145的视线中，在z = 0.3121±0.0003处显示出[O III] λ4958和λ5007。我们认为这个天体最有可能对21厘米的吸收负责，因为它比Bergeron和boiss<e:1>发现的两个星系更接近QSO视线。
We report the discovery of two low-redshift H I 21 cm absorbers, one at z = 0.2212 toward the zem = 0.630 quasar OI 363 (B0738+313), and the other at z = 0.3127 toward PKS B1127-145 (zem = 1.187). Both were found during a survey of Mg II–selected systems at redshifts 0.2 < z < 1 using the new UHF-high system at the Westerbork Synthesis Radio Telescope. New Hubble Space Telescope Faint Object Spectrograph observations also identify both systems as damped Lyα (DLA) absorbers. By comparing the column density from the DLA line with that from the H I 21 cm line, we calculate the spin temperature, Ts, of the two systems. We find Ts ≈ 1000 K for both these low-redshift absorbers. For the z = 0.3127 system toward PKS B1127-145, two galaxies have been previously identified with emission lines at the absorber redshift by Bergeron &Boissé, with the galaxy at a closer projected distance to the quasar assumed to be responsible for the absorption system. An ESO New Technology Telescope/EFOSC2 spectrum of a third, fainter companion at 3.″9, or 11 h kpc, from the line of sight of PKS B1127-145 reveals [O III] λ4958 and λ5007 at z = 0.3121 ± 0.0003. We consider this object the most likely to be responsible for the 21 cm absorption, as it is much closer to the QSO sight line than the two galaxies identified by Bergeron &Boissé.