Column density distribution and cosmological mass density of neutral gas: Sloan Digital Sky Survey-III Data Release 9
Abstract
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 ωgdla ≈ 10-3, evolving only mildly over the past 12 billion years.
Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/L1- Publication:
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Astronomy and Astrophysics
- Pub Date:
- November 2012
- DOI:
- 10.1051/0004-6361/201220259
- arXiv:
- arXiv:1210.1213
- Bibcode:
- 2012A&A...547L...1N
- Keywords:
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- cosmology: observations;
- quasars: absorption lines;
- galaxies: evolution;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Accepted for publication as Letter to the Editor in A&