Galaxies at a redshift of ~0.5 around three closely spaced quasar sightlines
Galaxies at a redshift of ~0.5 around three closely spaced quasar sightlines
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围绕三个间隔很近的类星体视线的红移约为 0.5 的星系
DOI：
10.1111/j.1365-2966.2009.15963.x
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发表时间：
2010
影响因子：
4.8
通讯作者：
Crighton N
中科院分区：
文献类型：
--
作者：
Crighton N
我们利用哈勃太空望远镜观测到的一组具有ZEM≈1的近距离背景类恒星天体(QSO)，研究了星系和星际介质之间的关系。使用一种新的分组算法，我们确定了三个类星体视线上可能存在物理联系的星系组和吸收体。与我们在99.9%的置信度水平下随机分布的吸收体所预期的数量相比，这类基团的数量过多。对使用流体动力学模拟产生的模拟光谱进行了同样的搜索，我们发现绝大多数这样的基团出现在模拟的密集区域。我们发现，模拟中的atz<；0.5基团通常跟踪大规模的丝状结构，如在∼30H−1Mpc区域中Hicolum密度的投影2D分布中所见。我们发现了一个可能的亚阻尼莱曼α系统，在z=0.557处，它显示出强的、低电离的金属吸收线。之前对这三条视线的吸收分析将这些金属线归因于Hi。我们表明，即使考虑到新的谱线标识，仍有证据表明平面结构在三条视线上具有∼1MPC的吸收。我们发现了一个atz=0.2272的星系，在两条视线上都有相关的金属吸收，每条视线都有200kpc的距离。通过约束星系的恒星形成历史，我们证明了导致金属吸收的气体可能是在2 Gyr前的恒星形成爆发期间被星系浓缩和抛射出来的。
We examine the relationship between galaxies and the intergalactic medium atz< 1 using a group of three closely spaced background quasi-stellar objects (QSOs) withzem≈ 1 observed with theHubble Space Telescope. Using a new grouping algorithm, we identify groups of galaxies and absorbers across the three QSO sightlines that may be physically linked. There is an excess number of such groups compared to the number we expect from a random distribution of absorbers at a confidence level of 99.9 per cent. The same search is performed with mock spectra generated using a hydrodynamical simulation, and we find that the vast majority of such groups arise in dense regions of the simulation. We find that atz< 0.5, groups in the simulation generally trace the large-scale filamentary structure as seen in the projected 2D distribution of the Hicolumn density in an ∼30h−1Mpc region. We discover a probable sub-damped Lyman α system atz= 0.557 showing strong, low-ionization metal absorption lines. Previous analyses of absorption across the three sightlines attributed these metal lines to Hi. We show that even when the new line identifications are taken into account, evidence remains for planar structures with scales of ∼1 Mpc absorbing across the three sightlines. We identify a galaxy atz= 0.2272 with associated metal absorption in two sightlines, each 200 kpc away. By constraining the star formation history of the galaxy, we show that the gas causing this metal absorption may have been enriched and ejected by the galaxy during a burst of star formation 2 Gyr ago.