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首页> 外文期刊>The Astrophysical journal >DOUBLE-DAMPED Lyα ABSORPTION: A POSSIBLE LARGE NEUTRAL HYDROGEN GAS FILAMENT NEAR REDSHIFT z = l~1
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DOUBLE-DAMPED Lyα ABSORPTION: A POSSIBLE LARGE NEUTRAL HYDROGEN GAS FILAMENT NEAR REDSHIFT z = l~1

机译：双阻尼Lyα吸收：可能的大中性氢气体细丝在Redshift附近z = l〜1

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摘要

We report the discovery of two damped Lyα systems (DLAs) near redshift z = 1 along a single quasar sight line (Q1727+5302) with neutral hydrogen column densities of N_(H Ⅰ) = (1.45 ± 0.15) x 10~(21) and (2.60 ± 0.20) x 10~(21) atoms cm~(-2). Their sight line velocity difference of 13,000 km s~(-1) corresponds to a proper separation of 106 h_(70)~(-1) Mpc if interpreted as the Hubble flow (Ω_m = 0.3, Ω_Λ = 0.7). The random probability of such an occurrence is significantly less than 3%. Follow-up spectroscopy reveals neutral gas-phase Zn abundances of [Zn/H] = -0.58 ± 0.15 (26.5% solar) and -1.32 ± 0.28 (4.7% solar), respectively. The corresponding Cr abundances are [Cr/H] = -1.26 ± 0.15 (5.5% solar) and -1.77 ± 0.28 (1.7% solar), respectively, which is evidence for depletion onto grains. Follow-up IR images show the two most likely DLA galaxy candidates to have impact parameters of ≈ 22 and ≈32 h_(70)~(-1) kpc if near z = 1. They are significantly underluminous relative to the galaxy population at z = 1. To investigate the possibility of additional high-N_(H Ⅰ) absorbers, we have searched the Sloan Digital Sky Survey database for z > 1 quasars within 30' of the original sight line. Five were found, and two show strong Mg Ⅱ-Fe Ⅱ absorption near z = 1, consistent with classical damped Lyα absorption ≈37% of the time, but almost always N_(H Ⅰ) > 10~(19) atoms cm~(-2). Consequently, this rare configuration of four high-N_(H Ⅰ) absorbers with a total sight line velocity extent of 30,600 km s~(-1) may represent a large filament-like structure stretching over a proper distance of 241 h_(70)~(-1) Mpc along our sight line, and a region in space capable of harboring excessive amounts of neutral gas. Future studies of this region of the sky are encouraged.
机译：我们报告了在一个单类星体视线（Q1727 + 5302）的红移z = 1附近发现了两个阻尼的Lyα系统（DLA），中性氢柱密度为N_（HⅠ）=（1.45±0.15）x 10〜（21） ）和（2.60±0.20）x 10〜（21）原子cm〜（-2）。如果将其视作哈勃流（Ω_m= 0.3，Ω_Λ= 0.7），则它们的视线速度差13,000 km s〜（-1）对应于106 h_（70）〜（-1）Mpc的适当距离。这种情况的随机概率显着小于3％。后续光谱显示中性气相锌丰度分别为[Zn / H] = -0.58±0.15（太阳为26.5％）和-1.32±0.28（太阳为4.7％）。相应的Cr丰度分别为[Cr / H] = -1.26±0.15（日照5.5％）和-1.77±0.28（日照1.7％），这证明了谷物的损耗。后续的红外图像显示，如果z接近1，则两个最可能的DLA星系候选者的撞击参数分别为≈22和≈32 h_（70）〜（-1）kpc。相对于z处的银河种群，它们的光通量明显不足= 1.为了研究额外的高N_（HⅠ）吸收剂的可能性，我们在斯隆数字天空测量数据库中搜索了原始视线30'内z> 1类星体。发现了五个，其中两个在z = 1附近显示出强大的MgⅡ-FeⅡ吸收率，与经典的阻尼Lyα吸收率一致，≈37％的时间，但几乎总是N_（HⅠ）> 10〜（19）原子cm〜（ -2）。因此，这种稀有的四个高N_（HⅠ）吸收体的总视线速度范围为30,600 km s〜（-1）的结构可能代表在适当的241 h_（70）距离上伸展的大丝状结构。沿着视线的〜（-1）Mpc，以及空间中能够容纳过量中性气体的区域。鼓励对这一天空地区的未来研究。

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