Double-Damped Lyman Alpha Absorption: A Possible Large Neutral Hydrogen Gas Filament Near Redshift z=1

Abstract

We report the discovery of two damped Ly-alpha absorption-line systems (DLAs) near redshift z=1 along a single quasar sightline (Q1727+5302) with neutral hydrogen column densities of N(HI) = (1.45\pm0.15)\times10^{21} and (2.60\pm0.20)\times10^{21} atoms/cm2. Their sightline velocity difference of 13,000 km/s corresponds to a proper separation of 106h_{70}^{-1} Mpc if interpreted as the Hubble flow (Omega_m=0.3, Omega_Lambda=0.7). The random probability of such an occurrence is significantly less than 3%. With follow-up spectroscopy, we find [Zn/H] = -0.58\pm0.15 (26.5% solar) and -1.32\pm0.28 (4.7% solar), respectively, and [Cr/H] = -1.26\pm0.15 (5.5% solar) and -1.77\pm0.28 (1.7% solar), respectively, which is evidence for depletion onto grains. Follow-up IR images show the two most likely DLA galaxy candidates to have impact parameters of 22h_{70}^{-1} kpc and 32h_{70}^{-1} kpc if near z=1. They are significantly underluminous relative to the galaxy population at z=1. To investigate the possibility of additional high-N(HI) absorbers we have searched the SDSS database for z>1 quasars within 30 arcmin of the original sightline. Five were found, and two show strong MgII-FeII absorption near z=1, consistent with classical DLA absorption approx 37% of the time, but almost always N(HI) > 10^{19} atoms/cm2. Consequently, this rare configuration of four high-N(HI) absorbers with a total sightline velocity extent of 30,600 km/s may represent a large filament-like structure stretching over a proper distance of 241h_{70}^{-1} Mpc along our sightline, and a region in space capable of harboring excessive amounts of neutral gas. Future studies of this region of the sky are encouraged.

arXiv commentApJL, accepted

References in corpus (21)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• The Optical and Near-Infrared Properties of Galaxies: I. Luminosity and Stellar Mass Functions
• Galaxies and Intergalactic Matter at Redshift z~3: Overview
• K and evolutionary corrections from UV to IR
• The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• Surveys for z > 3 Damped Lyman-alpha Absorption Systems
• The evolution of Omega(HI) and the epoch of formation of damped Lyman-alpha absorbers
• The Sloan Digital Sky Survey Quasar Catalog I. Early Data Release
• Low-Redshift Damped Lyman Alpha Galaxies Toward the Quasars B2 0827+243, PKS 0952+179, PKS 1127-145, and PKS 1629+120
• The Distribution of Lya-Emitting Galaxies at z=2.3
• Correlations in the orientations of galaxy clusters
• The Luminosity Function of QSO Host Galaxies
• Distinct Abundance Patterns in Multiple Damped Ly-alpha Galaxies: Evidence for Truncated Star Formation?
• Damped Lyman Alpha Gas Metallicities at Redshifts z=0.9-2.0 from SDSS Spectra
• The K band galaxy luminosity functions of three massive high redshift clusters of galaxies
• Unusual Metal Abundances in a Pair of Damped Lyman Alpha Systems at z~2
• Dynamical Mass Estimates of Large-Scale Filaments in Redshift Surveys
• The B band luminosities of QSO host galaxies
• First Investigation of the Clustering Environment of Damped Lyman Alpha Absorbers at z=4
• Clustering of galaxies at z=3 around the probable Damped Ly-alpha absorber towards QSO APM 08279+5255

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• The Bimodal Metallicity Distribution of the Cool Circumgalactic Medium at z<1
• The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
• Metals and Dust in Intermediate-redshift Damped Ly-alpha Galaxies
• A Groundbased Imaging Study of Galaxies Causing DLA, subDLA, and LLS Absorption in Quasar Spectra
• The COS CGM Compendium. II: Metallicities of the Partial and Lyman Limit Systems at z<1
• The chemistry of the most metal-rich damped Lyman $\alpha$ systems at z$\sim 2$ II. Context with the Local Group
• Probing the metallicity and ionization state of the circumgalactic medium at z~6 and beyond with OI absorption
• Elemental Abundances in Two High Column Density Damped Lyman Alpha Systems at z < 1.5
• An excess of damped Lyman alpha galaxies near QSOs
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• Discovery of a Damped Ly-alpha System in a Low-z Galaxy Group: Possible Evidence for Gas Inflow and Nuclear Star Formation
• First Detection of NaI D lines in High-Redshift Damped Lyman-alpha Systems
• Stellar Filaments in Self-Interacting Brans-Dicke Gravity
• A Damped Ly-alpha Absorption-line System in an Apparent Void at Redshift 2.38