Quasars probing quasars. VII. The pinnacle of the cool circumgalactic medium surrounds massive z ∼ 2 galaxies.
PROCHASKA J.X., LAU M.W. and HENNAWI J.F.
Abstract (from CDS):
We survey the incidence and absorption strength of the metal-line transitions C II 1334 and C IV 1548 from the circumgalactic medium (CGM) surrounding z ∼ 2 quasars, which act as signposts for massive dark matter halos Mhalo~ 1012.5 M☉. On scales of the virial radius (rvir~ 160 kpc), we measure a high covering fraction fC= 0.73±0.10 to strong C II 1334 absorption (rest equivalent width W1334 ≥ 0.2 Å), implying a massive reservoir of cool (T ∼ 104 K) metal enriched gas. We conservatively estimate a metal mass exceeding 108 M☉. We propose that these metals trace enrichment of the incipient intragroup/intracluster medium that these halos eventually inhabit. This cool CGM around quasars is the pinnacle among galaxies observed at all epochs, as regards covering the fraction and average equivalent width of H I Lyα 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 Mg II absorption along random quasar sightlines. Last, we detect an excess of strong C IV 1548 absorption (W1548 ≥ 0.3 Å) over random incidence to the 1 Mpc physical impact parameter and measure the quasar-C IV cross-correlation function: ζCIV -Q(r) = (r/r0)–γ with r0 = 7.5–1.4+2.8 h–1 Mpc and γ = 1.7–0.2+0.1. Consistent with previous work on larger scales, we infer that this highly ionized C IV gas traces massive (1012 M☉) halos.
galaxies: clusters: intracluster medium - intergalactic medium - quasars: absorption lines
VizieR on-line data:
<Available at CDS (J/ApJ/796/140): table1.dat table2.dat table5.dat>