A New Constraint on the Physical Nature of Damped Lyman Alpha Systems

Abstract

The formation and evolution of galaxies require large reservoirs of cold, neutral gas. The damped Lya systems (DLAs), seen in absorption towards distant quasars and gamma-ray bursts, are predicted to be the dominant reservoirs for this gas. Detailed properties of DLAs have been studied extensively for decades with great success. However, their size, fundamental in understanding their nature, has remained elusive, as quasar and gamma-ray-burst sightlines only probe comparatively tiny areas of the foreground DLAs. Here, we introduce a new approach to measure the full extent of DLAs in the sightlines toward extended background sources. We present the discovery of a high-column-density (log N(HI) = 21.1 +/-0.4 cm^-2) DLA at z ~ 2.4 covering 90-100% of the luminous extent of a line-of-sight background galaxy. Estimates of the size of the background galaxy range from a minimum of a few kpc^2, to ~100 kpc^2, and demonstrate that high-column density neutral gas can span continuous areas 10^8 - 10^10 times larger than previously explored in quasar or gamma-ray burst sightlines. The DLA presented here is the first from a sample of DLAs in our pilot survey that searches Lyman break and Lyman continuum galaxies at high redshift. The low luminosities, large sizes, and mass contents (>~10^6 - 10^9 M_solar) implied by this DLA and the early data suggest that DLAs contain the necessary fuel for galaxies, with many systems consistent with relatively massive, low-luminosity primeval galaxies.

4 pages, 3 figures, 1 table, accepted to ApJ Letters

References in corpus (7)

• Exploring the z=3-4 massive galaxy population with ZFOURGE: the prevalence of dusty and quiescent galaxies
• Predictions for the relation between strong HI absorbers and galaxies at redshift 3
• Directly imaging damped Ly-alpha galaxies at z>2. III: The star formation rates of neutral gas reservoirs at z~2.7
• The UV, Lyman-alpha, and dark matter halo properties of high redshift galaxies
• Lyman continuum galaxies and the escape fraction of Lyman break galaxies
• Coincident, 100 kpc-scale damped Lyman alpha absorption towards a binary QSO: how large are galaxies at z ~ 3?
• Close Galaxy Pairs at z = 3: A Challenge to UV Luminosity Abundance Matching

Cited by in corpus (16)

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• Galaxies Probing Galaxies in PRIMUS - I. Sample, Spectroscopy, and Characteristics of the z~0.5 MgII-Absorbing Circumgalactic Medium
• Galaxies Probing Galaxies in PRIMUS - II. The Coherence Scale of the Cool Circumgalactic Medium
• Spatially Resolved Metal Gas Clouds
• J1721$+$8842: a gravitationally lensed binary quasar with a proximate damped Lyman-$\alpha$ absorber
• Resolving the HI in Damped Lyman-α systems that power star-formation
• Eclipsing damped Ly$\alpha$ systems in the Sloan Digital Sky Survey Data Release 12
• The relationship between gas and galaxies at z<1 using the Q0107 quasar triplet
• Discovery of a Damped Lya Absorber at z = 3.3 along a galaxy sight-line in the SSA22 field
• Discovery of a Low-Redshift Damped Ly$\alpha$ System in a Foreground Extended Disk Using a Starburst Galaxy Background Illuminator
• Exploring Damped Lyman-$\alpha$ System Host Galaxies using Gamma-ray Bursts
• A search for Ly-alpha emitters around a concentrated-region of strong Ly-alpha absorbers at z=2.3
• The multiple coherence scales of C IV at cosmic noon
• Constraining the Size of the Circumgalactic Medium Using the Transverse Autocorrelation Function of C IV Absorbers in Paired Quasar Spectra
• Intergalactic Medium Tomography with the Sunburst Arc