Zabs = 2.05时DLA中的多组分H2：通过观测和数值模型得出的物理条件
Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models
摘要：
我们进行详细的光谱分析和数值模拟的H2轴承阻尼莱曼α吸收体（DLA）在zabs = 2.05对类星体FBQS J2340-0053。金属吸收特征来自分布在$Δv_{90}$ = 114 km s $^{-1}$上的14个组分，其中7个含有H2。原子和分子物种的柱密度是通过它们的吸收线的Voigt轮廓分析得到的。我们测得总N（H1）、N（H2）和N（HD）分别为20.35 ± 0.05、17.99 ± 0.05和14.28 ± 0.08（log cm $^{-2}$）。H2在基态振动态的最低六个旋转能级中被检测到。DLA具有金属性，Z = 0.3 Z $_\sun$（[S/H] = -0.52+/-0.06）和尘气比，$κ$ = 0.34+/-0.07。H2分量的数值模型被单独约束以理解DLA的物理结构。我们认为DLA受到$\sim$ 10 $^{-15.37}$ s $^{-1}$的超银河系背景辐射和宇宙线电离率的影响。DLA中的尘埃颗粒比银河系星际介质中的颗粒要小。H2组分的内部分子区域的密度、温度和气压分别在30-120 cm $^{-3}$、140-360 K和7，000 - 23，000 cm $^{-3}$ K的范围内。微湍流压力是总压力的重要组成部分，并且在这些最内部区域中可以发挥重要作用。我们的H2组分模型使我们能够约束组分方面的N（H I）以及硫、硅、铁和碳的元素丰度。我们推导出DLA的H2轴承部分的视线厚度为7.2 pc。
英文摘要：
We perform detailed spectroscopic analysis and numerical modelling of an H2-bearing damped Lyman-alpha absorber (DLA) at zabs = 2.05 towards the quasar FBQS J2340-0053. Metal absorption features arise from fourteen components spread over $Δv_{90}$ = 114 km s$^{-1}$, seven of which harbour H2. Column densities of atomic and molecular species are derived through Voigt profile analysis of their absorption lines. We measure total N(H I), N(H2) and N(HD) to be 20.35+/-0.05, 17.99+/-0.05 and 14.28+/-0.08 (log cm$^{-2}$) respectively. H2 is detected in the lowest six rotational levels of the ground vibrational state. The DLA has metallicity, Z = 0.3 Z$_\sun$ ([S/H] = -0.52+/-0.06) and dust-to-gas ratio, $κ$ = 0.34+/-0.07. Numerical models of the H2 components are constrained individually to understand the physical structure of the DLA. We conclude that the DLA is subjected to the metagalactic background radiation and cosmic ray ionization rate of $\sim$ 10$^{-15.37}$ s$^{-1}$. Dust grains in this DLA are smaller than grains in the Galactic interstellar medium. The inner molecular regions of the H2 components have density, temperature and gas pressure in the range 30-120 cm$^{-3}$, 140-360 K and 7,000-23,000 cm$^{-3}$ K respectively. Micro-turbulent pressure is a significant constituent of the total pressure, and can play an important role in these innermost regions. Our H2 component models enable us to constrain component-wise N(H I), and elemental abundances of sulphur, silicon, iron and carbon. We deduce the line-of-sight thickness of the H2-bearing parts of the DLA to be 7.2 pc.
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