Hot halos around high redshift protogalaxies : Observations of O VI and N V absorption in damped Lyman-α systems
Hot halos around high redshift protogalaxies : Observations of O VI and N V absorption in damped Lyman-α systems
复制标题
DOI：
10.1051/0004-6361:20066157
复制
发表时间：
2007-01
影响因子：
6.5
通讯作者：
A. Fox;P. Petitjean;C. Ledoux;R. Srianand
中科院分区：
文献类型：
--
作者：
A. Fox;P. Petitjean;C. Ledoux;R. Srianand
目标。我们研究了与阻尼莱曼-α（DLA）系统（z = 2.1−3.1）相关的高度电离气体（等离子体）。方法.我们在一个包含35个DLA系统的甚大望远镜/紫外-可见中阶梯光谱仪（VLT/UVES）样品中寻找了O_（vi）的吸收和相应的Si_（iv）、C_（iv）和Nv，其数据覆盖了O_（vi）在S /N > 10的范围。然后，我们使用光学深度剖面比较和电离建模来研究等离子体的性质，相结构和起源。结果我们报告了12个DLAs（9个干预和3个在19。δ t0>21.1，并且logN Warmii > 19。4t 0>20.9。因此，平均而言，热相和暖相分别包含DLAs中中性相的重子质量的>40%和>20%。结论.如果Ovi相的温度为10.6 K，则sofOvi = Ovi/O-0。2.在高红移处，等离子体对金属收支有点火贡献。在莱曼极限系统（17.0 < NHi < 20.3的类星体吸收体）中对O vi的额外搜索对于确定隐藏在z = 2的热晕中的重子和金属的总量是必要的。
Aims. We present a study of the highly ionized gas (plasma) associated with damped Lyman-α (DLA) systems at z = 2.1−3.1. Methods. We search for O vi absorption and corresponding Si iv ,C iv ,a nd Nv in a Very Large Telescope/Ultraviolet-Visible Echelle Spectrograph (VLT/UVES) sample of 35 DLA systems with data covering O vi at S /N > 10. We then use optical depth profile comparisons and ionization modelling to investigate the properties, phase structure, and origin of the plasma. Results. We report twelve DLAs (nine intervening and three at 19. 5t o>21.1, and logN Warmii > 19. 4t o>20.9. On average, the hot and warm phases thus contain >40% and >20% of the baryonic mass of the neutral phase in DLAs, respectively. Conclusions. If the temperature in the O vi phase is ≈10 6 Ka nd sofOvi = Ovi/O � 0. 2, the plasma can make as ignif icant contribution to the metal budget at high redshift. Additional searches for O vi in Lyman Limit Systems (QSO absorbers with 17.0 < NHi < 20.3) will be necessary to determine the total quantity of baryons and metals hidden in hot halos at z ≈ 2.