Dissecting the gaseous halos of z ∼ 2 damped Lyα systems with close quasar pairs
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
- MIT-Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82072 (United States)
We use spectroscopy of close pairs of quasars to study diffuse gas in the circumgalactic medium (CGM) surrounding a sample of 40 damped Lyα systems (DLAs). The primary sightline in each quasar pair probes an intervening DLA in the redshift range 1.6 10{sup 17.2} cm{sup −2}) to be ≳30% within R{sub ⊥}<200 kpc. Strong Si ii λ1526 absorption with equivalent width W{sub 1526}>0.2 Å occurs with an incidence f{sub C}(W{sub 1526}>0.2 A-ring )=20{sub −8}{sup +12}% within R{sub ⊥}<100 kpc, indicating that Si ii absorption associated with DLAs probes material within a physical distance R{sub 3D}≲30 kpc. However, we find that strong C iv λ1548 absorption is ubiquitous in these environments (f{sub C}(W{sub 1548}>0.2 A-ring )=57{sub −13}{sup +12}% within R{sub ⊥}<100 kpc), and in addition exhibits a high degree of kinematic coherence on scales up to ∼175 kpc. We infer that this high-ionization material arises predominantly in large, quiescent structures extending beyond the scale of the DLA host dark matter halos rather than in ongoing galactic winds. The Lyα equivalent width in the DLA-CGM is anticorrelated with R{sub ⊥} at >98% confidence, suggesting that DLAs arise close to the centers of their host halos rather than on their outskirts. Finally, the average Lyα, and C ii and C iv equivalent widths measured as a function of R{sub ⊥} are consistent with those measured around z ∼ 2 Lyman break galaxies. Assuming that DLAs trace a galaxy population at lower masses and luminosities, this finding implies that the absorption strength of cool circumgalactic material has a weak dependence on dark matter halo mass at M{sub h}≲10{sup 12} M{sub ⊙}.
- OSTI ID:
- 22882882
- Journal Information:
- Astrophysical Journal, Vol. 808, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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