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J/ApJ/796/140  Circumgalactic medium surrounding z∼2 quasars  (Prochaska+, 2014)

Quasars probing quasars. VII. The pinnacle of the cool circumgalactic medium surrounds massive z∼2 galaxies. Prochaska J.X., Lau M.W., Hennawi J.F. <Astrophys. J., 796, 140 (2014)> =2014ApJ...796..140P (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Clusters, galaxy ; Redshifts ; Equivalent widths Keywords: galaxies: clusters: intracluster medium; intergalactic medium quasars: absorption lines Abstract: 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) 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. Description: The sample of quasar pairs analyzed here is a subset of the sample studied in QPQ6 (Cantalupo et al. 2014Natur.506...63C) for H I Lyα absorption. Specifically, we have restricted the current study to those pairs where the signal-to-noise ratio (S/N) at H I Lyα exceeds 9.5 per rest-frame Å. This facilitates a more precise evaluation of H I Lyα and generally insures sufficient S/N redward of Lyα for the metal-line analysis. Quasar emission redshifts are taken directly from QPQ6 (Cantalupo et al. 2014Natur.506...63C), following the methodology described in that manuscript. Briefly, we adopt a custom line-centering algorithm to centroid one or more far-UV emission lines and adopt the analysis of Shen et al. (2007, J/AJ/133/2222) to combine these measurements and assess systematic uncertainty in the final value. The median emission redshift of the 427 pairs is zemmedian=2.35 and the median uncertainty in the redshift measurements is ∼520 km/s. The impact parameters range from R=39 kpc to 1 Mpc, with 52 pairs having R<200 kpc. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 81 524 QPQ7 Spectra table2.dat 81 427 QPQ7 EW Measurements table5.dat 53 223 SDSS C IV Survey
See also: VII/69 : Asiago Catalogue of QSOs (Barbieri+ 1983) VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004) J/AJ/131/1 : Binary quasars in the SDSS (Hennawi+, 2006) J/AJ/133/2222 : Clustering of high-redshift QSOs from SDSS (Shen+, 2007) J/MNRAS/401/2715 : CIV column densities in z<2.5 QSOs (D'odorico+, 2010) J/ApJ/762/L19 : Quasar pairs spectroscopy (Prochaska+, 2013) J/ApJ/776/136 : QPQ VI. HI absorption of z∼2 quasars (Prochaska+, 2013) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 19 A19 --- b/gQ Background quasar identifier (JHHMMSS.ss+DDMMSS.s) 21- 39 A19 --- f/gQ Foreground quasar identifier (JHHMMSS.ss+DDMMSS.s) 41- 46 F6.4 --- zfg Foreground quasar redshift 48- 50 I3 kpc Rphys Impact parameter 52- 71 A20 --- Instr Instrument used in the observation 73- 81 A9 0.1nm Wave Wavelength coverage of Instr in Angstroms (1)
Note (1): Rest-frame wavelengths at the f/g quasar redshift where the spectra of the b/g quasar exceeds S/N>5 per pixel.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 19 A19 --- f/gQ Foreground quasar identifier (JHHMMSS.ss+DDMMSS.s) 21- 39 A19 --- b/gQ Background quasar identifier (JHHMMSS.ss+DDMMSS.s) 41- 43 I3 kpc Rphys Impact parameter 45- 49 F5.3 --- zfg Foreground quasar redshift 51- 55 I5 km/s delv Velocity offset (1) 57- 62 F6.3 0.1nm W1334 ? Equivalent width of C II 1334Å line (G1) 64- 68 F5.3 0.1nm e_W1334 ? Uncertainty in W1334 (G1) 70- 75 F6.3 0.1nm W1548 ? Equivalent width of C IV 1548Å line (G1) 77- 81 F5.3 0.1nm e_W1548 ? Uncertainty in W1548 (G1)
Note (1): From zLyα to zfg. Note that absorption lines were assessed only for data with S/NLyα>9.5.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 19 A19 --- Quasar Quasar identifier (JHHMMSS.ss+DDMMSS.s) 21- 25 F5.3 --- zq Quasar emission redshift 27- 31 F5.3 --- zstart Starting redshift (1) 33- 37 F5.3 --- zend Ending redshift (2) 39- 43 F5.3 --- zCIV ? C IV 1548 line redshift 45- 48 F4.2 0.1nm WCIV ? Equivalent width of C IV 1548Å line (G1) 50- 53 F4.2 0.1nm e_WCIV ? Uncertainty in WCIV
Note (1): For the C IV search. Defined as (1+zq)*1238.8/1548.195-1. Note (2): For the C IV search. Defined as 4000 km/s blueward of the quasar redshift.
Global notes: Note (G1): In units of Angstroms.
History: From electronic version of the journal References: Ho et al. Paper I 2017ApJ...835..267H Hennawi et Prochaska Paper II 2007ApJ...655..735H Prochaska et Hennawi Paper III 2009ApJ...690.1558P Hennawi et Prochaska Paper IV 2013ApJ...766...58H Prochaska et al. Paper V 2013ApJ...762L..19P, Cat. J/ApJ/762/L19 Prochaska et al. Paper VI 2013ApJ...776..136P, Cat. J/ApJ/776/136 Lau et al. Paper VIII 2016ApJS..226...25L
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 11-Aug-2017
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