A search for H i 21 cm absorption in strong Mg ii absorbers in the redshift desert
A search for H i 21 cm absorption in strong Mg ii absorbers in the redshift desert
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DOI：
10.1111/j.1365-2966.2009.14661.x
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发表时间：
2009-03
影响因子：
4.8
通讯作者：
N. Kanekar;J. Prochaska;S. Ellison;J. N. C. N. R. A. Observatory-J.-N.-C.-N.-R.-A.-Observatory-102497302;Usa UC-Santa Cruz;Usa University of Victoria;Canada Max-Planck Institute for Astrophysics;India.
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文献类型：
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作者：
N. Kanekar;J. Prochaska;S. Ellison;J. N. C. N. R. A. Observatory-J.-N.-C.-N.-R.-A.-Observatory-102497302;Usa UC-Santa Cruz;Usa University of Victoria;Canada Max-Planck Institute for Astrophysics;India.
本文报道了55个强Mg Ⅱ λ2796吸收体中H Ⅰ 21 cm吸收红移的深度搜索结果（具有W λ2796 0 > 0.5 A）在中间红移，0.58 3σ显著性在32个其他Mg II吸收体中，其中26个提供了H I 21 cm光学深度的强上限，τ 3σ [800 × f ] K（其中f是覆盖因子），如果H I柱密度≥2 × 10 20 cm −2，即如果吸收体是阻尼莱曼α系统（DLA）。样本中其余13个系统的数据受到无线电频率干扰的影响，因此没有用处。Mg II吸收体中的两个，在zabs = 1.4106朝向2003 - 025和在zabs = 0.9115朝向2149+212处，是已知的DLA。我们用GMRT探测到了2003 - 025附近的H I 21 cm吸收，并估算了DLA的自旋温度为Ts = [（905 ± 380）× f ]K .相反，2149+212的GBT观测导致没有检测到H I 21 cm吸收，从而产生3σ极限Ts> [2700 × f ]K。排除“关联”系统（类星体红移在3000 km s −1以内），
We report results from a deep search for redshifted H I 21 cm absorption in 55 strong Mg IIλ2796 absorbers (having W λ2796 0 > 0.5 A) at intermediate redshifts, 0.58 3σ significance in 32 other Mg II absorbers, with 26 of these providing strong upper limits to the H I 21 cm optical depth, τ 3σ [800 × f ] K (where f is the covering factor), if the H I column density is ≥2 × 10 20 cm −2 , i.e. if the absorber is a damped Lyman α system (DLA). Data on the remaining 13 systems of the sample were affected by radio frequency interference and were hence not useful. Two of the Mg II absorbers, at zabs ∼ 1.4106 towards 2003−025 and at zabs ∼ 0.9115 towards 2149+212, are known DLAs. We detect H I 21 cm absorption towards 2003−025 with the GMRT and estimate the spin temperature of the DLA to be T s = [(905 ± 380) × f ]K . Conversely, the GBT observations of 2149+212 resulted in a non-detection of H I 21 cm absorption, yielding the 3σ limit T s > [2700 × f ]K . Excluding ‘associated’ systems (within 3000 km s −1 of the quasar redshift), the detection rate