Using HST/COS/STIS and HIRES/Keck high-resolution spectra, we have studied a remarkable H I absorbing complex at z = 0.672 toward the quasar Q1317+277. The H I absorption has a velocity spread of Δv = 1600 km s^(–1), comprises 21 Voigt profile components, and resides at an impact parameter of D = 58 kpc from a bright, high-mass (log M_(vir)/M_☉ ≃ 13.7) elliptical galaxy that is deduced to have a 6 Gyr old, solar metallicity stellar population. Ionization models suggest the majority of the structure is cold gas surrounding a shock-heated cloud that is kinematically adjacent to a multi-phase group of clouds with detected C III, C IV, and O VI absorption, suggestive of a conductive interface near the shock. The deduced metallicities are consistent with the moderate in situ enrichment relative to the levels observed in the z ~ 3 Lyα forest. We interpret the H I complex as a metal-poor filamentary structure being shock heated as it accretes into the halo of the galaxy. The data support the scenario of an early formation period (z > 4) in which the galaxy was presumably fed by cold-mode gas accretion that was later quenched via virial shocking by the hot halo such that, by intermediate redshift, the cold filamentary accreting gas is continuing to be disrupted by shock heating. Thus, continued filamentary accretion is being mixed into the hot halo, indicating that the star formation of the galaxy will likely remain quenched. To date, the galaxy and the H I absorption complex provide some of the most compelling observational data supporting the theoretical picture in which accretion is virial shocked in the hot coronal halos of high-mass galaxies.
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机译：使用HST / COS / STIS和HIRES / Keck高分辨率光谱，我们研究了在z = 0.672处向类星体Q1317 + 277的一个显着的H I吸收配合物。 HI吸收的速度分布为Δv= 1600 km s ^（– 1），包括21个Voigt剖面分量，并且来自明亮的高质量（log M_（vir）/ M_☉13.7）推论为具有6 Gyr老太阳金属性恒星的椭圆星系。电离模型表明，该结构的大部分是围绕被激波加热的云团围绕的冷气体，该运动场在运动学上与检测到的C III，C IV和O VI吸收的多相云团运动相邻，这表明在激波附近存在导电界面。相对于z〜3Lyα森林中观察到的水平，推断的金属含量与中等程度的原位富集相一致。我们将H I配合物解释为贫金属的丝状结构，因为它会吸收到银河系的晕圈中，因此会受到冲击加热。数据支持早期形成阶段（z> 4）的情况，其中银河系大概是由冷态气体积聚提供的，后来通过热晕的病毒冲击使淬灭，从而通过中间的红移，使冷丝状积聚。冲击加热继续破坏天然气。因此，持续的丝状增生被混合到热晕中，这表明星系的恒星形成很可能保持淬灭状态。迄今为止，星系和H I吸收复合物提供了一些最引人注目的观测数据，支持了在高质量星系的热冠状晕中病毒体激增的理论图景。
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