类星体探测类星体VII。大质量z~2星系周围冷环银河系介质的顶点
Quasars Probing Quasars VII. The Pinnacle of the Cool Circumgalactic Medium Surrounds Massive z~2 Galaxies
摘要：
我们测量了z~2类星体周围的环星系介质（CGM）中金属线跃迁CII 1334和CIV的入射率和吸收强度，它们是大质量暗物质晕M_halo~10^12.5 Msun的路标.在维里半径（Mvir~ 160 kpc）的尺度上，我们测量到高覆盖分数fC=0.73+/-0.10到强CII吸收（静止等效宽度W1334>0.2A），这意味着大量的冷（T~10^4K）金属富集气体。我们保守地估计金属质量超过10^8兆太阳。我们建议这些金属微量富集的初期intragroup/intracluster介质，这些晕最终居住。这类星体周围的冷CGM是在所有时代观察到的星系中的顶峰，就覆盖率和HI Lya的平均等效宽度和低离子金属吸收而言。我们认为，这个冷CGM的属性主要反映晕质量，和其他因素，如反馈，恒星形成率，星系际介质的吸积是次要的。我们进一步估计，大质量z~2星系的CGM占了沿随机类星体视线的大部分强MgII吸收。最后，我们在1 Mpc的物理碰撞参量下探测到了超过随机入射的强CIV吸收（W 1548>0.3A），并测量了类星体CIV交叉关联函数：xi（r）=（r/r 0）^-g，其中r 0 = 7.5Mpc，g=1.7。与以前在更大尺度上的工作相一致，我们推断这种高度电离的CIV气体追踪了大质量（10^12 Msun）的晕。
英文摘要：
We survey the incidence and absorption strength of the metal-line transitions CII 1334 and CIV from the circumgalactic medium (CGM) surrounding z~2 quasars, which act as signposts for massive dark matter halos M_halo~10^12.5 Msun. On scales of the virial radius (Mvir~160kpc), we measure a high covering fraction fC=0.73+/-0.10 to strong CII absorption (rest equivalent width W1334>0.2A), implying a massive reservoir of cool (T~10^4K) metal enriched gas. We conservatively estimate a metal mass exceeding 10^8 Msun. We propose these metals trace enrichment of the incipient intragroup/intracluster medium that these halos eventually inhabit. This cool CGM around quasars is the pinnacle amongst galaxies observed at all epochs, as regards covering fraction and average equivalent width of HI Lya and low-ion metal absorption. We argue that the properties of this cool CGM primarily reflect the halo mass, and that other factors such as feedback, star-formation rate, and accretion from the intergalactic medium are secondary. We further estimate, that the CGM of massive, z~2 galaxies accounts for the majority of strong MgII absorption along random quasar sightlines. Lastly, we detect an excess of strong CIV absorption (W1548>0.3A) over random incidence to 1Mpc physical impact parameter and measure the quasar-CIV cross-correlation function: xi(r)=(r/r0)^-g with r0 = 7.5Mpc and g=1.7. Consistent with previous work on larger scales, we infer that this highly ionized CIV gas traces massive (10^12 Msun) halos.
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