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dc.contributor.authorProchaska, J. Xavier
dc.contributor.authorHennawi, Joseph F.
dc.contributor.authorLee, Khee-Gan
dc.contributor.authorCantalupo, Sebastiano
dc.contributor.authorBovy, Jo
dc.contributor.authorDjorgovski, S. G.
dc.contributor.authorEllison, Sara L.
dc.contributor.authorLau, Marie Wingyee
dc.contributor.authorMartin, Crystal L.
dc.contributor.authorMyers, Adam
dc.contributor.authorRubin, Kate H. R.
dc.contributor.authorSimcoe, Robert A.
dc.date.accessioned2014-08-06T16:41:01Z
dc.date.available2014-08-06T16:41:01Z
dc.date.issued2013-10
dc.date.submitted2013-06
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.urihttp://hdl.handle.net/1721.1/88545
dc.description.abstractWith close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the H I Lyα absorption transverse to luminous, z ~ 2 quasars at proper separations of 30 kpc < R [subscript ⊥] < 1 Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced H I Lyα absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Lyα equivalent width profile W = 2.3 Å (R [subscript ⊥]/100 kpc)[superscript –0.46]. We also observe a high ([~ over -] 60%) covering factor of strong, optically thick H I absorbers (H I column N[subscript HI] > 10[superscript 17.3] cm[superscript -2]) at separations R [subscript ⊥] < 200 kpc, which decreases to ~20% at R [subscript ⊥] [~ over -] 1 Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function ξ[subscript QA](r) = (r/r [subscript 0])[superscript γ] with a large correlation length r[subscript 0] = 12.5[+2.7 over -1.4] h[superscript -1] Mpc (comoving) and γ =1.68[+0.14 over -0.30]. The H I absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M [subscript halo] ≈ 10[superscript 12.5] M [subscript ☉] at z ~ 2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z ~ 2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.en_US
dc.language.isoen_US
dc.publisherIOP Publishingen_US
dc.relation.isversionofhttp://dx.doi.org/10.1088/0004-637X/776/2/136en_US
dc.rightsCreative Commons Attribution-Noncommercial-Share Alikeen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/4.0/en_US
dc.sourcearXiven_US
dc.titleQUASARS PROBING QUASARS. VI. EXCESS H I ABSORPTION WITHIN ONE PROPER Mpc OF z ~ 2 QUASARSen_US
dc.typeArticleen_US
dc.identifier.citationProchaska, J. Xavier, Joseph F. Hennawi, Khee-Gan Lee, Sebastiano Cantalupo, Jo Bovy, S. G. Djorgovski, Sara L. Ellison, et al. “QUASARS PROBING QUASARS. VI. EXCESS H I ABSORPTION WITHIN ONE PROPER Mpc OF z ∼ 2 QUASARS.” The Astrophysical Journal 776, no. 2 (October 7, 2013): 136.en_US
dc.contributor.departmentKavli Institute for Astrophysics and Space Researchen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Physicsen_US
dc.contributor.mitauthorSimcoe, Robert A.en_US
dc.relation.journalThe Astrophysical Journalen_US
dc.eprint.versionAuthor's final manuscripten_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsProchaska, J. Xavier; Hennawi, Joseph F.; Lee, Khee-Gan; Cantalupo, Sebastiano; Bovy, Jo; Djorgovski, S. G.; Ellison, Sara L.; Lau, Marie Wingyee; Martin, Crystal L.; Myers, Adam; Rubin, Kate H. R.; Simcoe, Robert A.en_US
dc.identifier.orcidhttps://orcid.org/0000-0003-3769-9559
mit.licenseOPEN_ACCESS_POLICYen_US


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