Volume 547, November 2012
|Number of page(s)||4|
|Published online||22 October 2012|
Column density distribution and cosmological mass density of neutral gas: Sloan Digital Sky Survey-III Data Release 9⋆
Institut d’Astrophysique de Paris, CNRS-UPMC, UMR 7095,
98bis bd Arago,
2 Lawrence Berkeley National Lab, 1 Cyclotron Rd, Berkeley, CA 94720, USA
3 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
4 Institute of Theoretical Physics, University of Zurich, 8057 Zurich, Switzerland
5 APC, CNRS UMR 7164, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
6 Apache Point Observatory, PO Box 59, Sunspot, NM 88349-0059, USA
7 Astronomy Department, University of Florida, 211 Bryant Space Science Center, PO Box 112055, Gainesville, FL 32611-2055, USA
8 Institut de Ciències del Cosmos, Universitat de Barcelona, Facultat de Física, Barcelona, Spain
9 Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
10 Institute of Cosmology and Gravitation, University of Portsmouth, UK
11 Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
12 Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
13 Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
14 Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
Received: 19 August 2012
Accepted: 3 October 2012
We present the first results from an ongoing survey for damped Lyman-α systems (DLAs) in the spectra of z > 2 quasars observed in the course of the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey (SDSS) III. Our full (non-statistical) sample, based on Data Release 9, comprises 12 081 systems with log N(H i) ≥ 20, out of which 6839 have log N(H i) ≥ 20.3. This is the largest DLA sample ever compiled, superseding that from SDSS-II by a factor of seven.
Using a statistical sub-sample and estimating systematics from realistic mock data, we probe the N(H i) distribution at ⟨z⟩ = 2.5. Contrary to what is generally believed, the distribution extends beyond 1022 cm-2 with a moderate slope of index ≈−3.5. This result matches the opacity-corrected distribution observed at z = 0 surprisingly well. The cosmological mass density of neutral gas in DLAs is found to be , evolving only mildly over the past 12 billion years.
Key words: cosmology: observations / quasars: absorption lines / galaxies: evolution
Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/L1
© ESO, 2012
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