Discovery of a Damped Ly-alpha Absorber at z = 3.3 along a Galaxy Sight-line in the SSA22 Field

Mawatari, K.; Inoue, A.K.; Kousai, K.; Hayashino, T.; Cooke, R.; Prochaska, J.X.; Yamada, T.; Matsuda, Y.

Abstract

Using galaxies as background light sources to map the Lya absorption lines is a novel approach to study Damped Lya Absorbers (DLAs). We report the discovery of an intervening z = 3.335 +- 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our Very Large Telescope/Visible Multi-Object Spectrograph survey in the SSA22 field. The measured DLA neutral hydrogen (HI) column density is log (NHI/cm^{-2}) = 21.68 +- 0.17. The DLA covering fraction over the extended background LBG is > 70% (2 sigma), yielding a conservative constraint on the DLA area of > 1 kpc^2. Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate (SFR) larger than a few Msun yr^{-1}, ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with Mstar > 5 x 10^{10} Msun or a heavily dust-obscured galaxy with E(B-V) > 2. The DLA may coincide with a large-scale overdensity of the spectroscopic LBGs. The occurrence rate of the DLA is compatible with that of DLAs found in QSO sight-lines.

Citation

Mawatari, K., Inoue, A., Kousai, K., Hayashino, T., Cooke, R., Prochaska, J., …Matsuda, Y. (2016). Discovery of a Damped Ly-alpha Absorber at z = 3.3 along a Galaxy Sight-line in the SSA22 Field. Astrophysical Journal, 817(2), Article 161. https://doi.org/10.3847/0004-637x/817/2/161

• Journal Article Type: Article
• Acceptance Date: Dec 18, 2015
• Online Publication Date: Jan 28, 2016
• Publication Date: Feb 1, 2016
• Deposit Date: Feb 20, 2017
• Publicly Available Date: Mar 28, 2017
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 817
• Issue: 2
• Article Number: 161
• DOI: https://doi.org/10.3847/0004-637x/817/2/161
• Public URL: https://durham-repository.worktribe.com/output/1363453
• Related Public URLs: https://arxiv.org/abs/1512.04625