A quasar reddened by a sub-parsec sized, metal-rich and dusty cloud in a damped Lyman-alpha absorber at z=2.13

Abstract

We present a detailed analysis of a red quasar at z=2.32 with an intervening damped Lyman-alpha absorber (DLA) at z=2.13. Using high quality data from the X-shooter spectrograph at ESO Very Large Telescope we find that the absorber has a metallicity consistent with Solar. We observe strong C I and H${}_2$ absorption indicating a cold, dense absorbing medium. Partial coverage effects are observed in the C I lines, from which we infer a covering fraction of $27\pm 6$ % and a physical diameter of the cloud of 0.1 pc. From the covering fraction and size, we estimate the size of the background quasar's broad line region. We search for emission from the DLA counterpart in optical and near-infrared imaging. No emission is observed in the optical data. However, we see tentative evidence for a counterpart in the H and K' band images. The DLA shows high depletion (as probed by [Fe/Zn]=-1.22) indicating that significant amounts of dust must be present in the DLA. By fitting the spectrum with various dust reddened quasar templates we find a best-fitting amount of dust in the DLA of $A(V{)}_{\mathrm{DLA}}=0.28\pm 0.01{|}_{\mathrm{stat}}\pm 0.07{|}_{\mathrm{sys}}$. We conclude that dust in the DLA is causing the colours of this intrinsically very luminous background quasar to appear much redder than average quasars, thereby not fulfilling the criteria for quasar identification in the Sloan Digital Sky Survey. Such chemically enriched and dusty absorbers are thus underrepresented in current samples of DLAs.

14 pages, accepted for publication in MNRAS

References in corpus (21)

• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• Velocity-Metallicity Correlation for high-z DLA Galaxies: Evidence for a Mass-Metallicity Relation?
• Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database
• Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-alpha, and Lyman-break Galaxies at z=3
• The UV Continuum of Quasars: Models and SDSS Spectral Slopes
• The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System
• Mining for Dust in Type 1 Quasars
• Extinction and metal column density of HI regions up to redshift z~2
• The color excess of quasars with intervening DLA systems- Analysis of the SDSS data release five
• Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?
• The chemistry of the most metal-rich damped Lyman $\alpha$ systems at z$\sim 2$ II. Context with the Local Group
• On the mass-metallicity relation, velocity dispersion and gravitational well depth of GRB host galaxies
• Dust Biasing of Damped Lyman Alpha Systems: a Bayesian Analysis
• The Magellan Uniform Survey of Damped Lyman alpha Systems II: Paucity of Strong Molecular Hydrogen Absorption
• The elusive HI-> H2 transition in high-z damped Lyman-alpha systems
• The High A(V) Quasar Survey: Reddened quasi-stellar objects selected from optical/near-infrared photometry - II
• Near Infrared Photometric properties of 130,000 Quasars: An SDSS-UKIDSS matched catalog
• Neutral atomic-carbon QSO absorption-line systems at z>1.5: Sample selection, HI content, reddening, and 2175 A extinction feature
• A Metal-Strong and Dust-Rich Damped \lya Absorption System toward the Quasar SDSS J115705.52+615521.7
• A catalogue of absorption-line systems in QSO spectra
• A study of purely astrometric selection of extragalactic point sources with Gaia

Cited by in corpus (39)

• The cosmic evolution of dust-corrected metallicity in the neutral gas
• The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
• Dust-depletion sequences in damped Lyman-α absorbers: a unified picture from low-metallicity systems to the Galaxy
• CO-dark molecular gas at high redshift: very large H${}_2$ content and high pressure in a low metallicity damped Lyman-alpha system
• Chemical abundances of damped Lyman alpha systems in the XQ-100 survey
• Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey
• Direct measurement of the [CI] luminosity to molecular gas mass conversion factor in high-redshift star-forming galaxies
• The Mean Metal-line Absorption Spectrum of DLAs in BOSS
• The effect of dust bias on the census of neutral gas and metals in the high-redshift Universe due to SDSS-II quasar colour selection
• The extended High A(V) Quasar Survey: Searching for dusty absorbers toward mid-infrared selected quasars
• Cold gas in the early Universe. Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy
• High Molecular Gas Masses in Absorption-selected Galaxies at $z\approx 2$
• A quasar hiding behind two dusty absorbers. Quantifying the selection bias of metal-rich, damped Lyman-alpha absorption systems
• J1721$+$8842: a gravitationally lensed binary quasar with a proximate damped Lyman-$\alpha$ absorber
• The high A_V Quasar Survey: A z=2.027 metal-rich damped Lyman-alpha absorber towards a red quasar at z=3.21
• Sub-damped Lyman alpha systems in the XQ-100 survey II -- Chemical evolution at 2.4<z<4.3
• Element Abundances in a Gas-rich Galaxy at z = 5: Clues to the Early Chemical Enrichment of Galaxies
• Evolution of cold gas at 2<z<5: a blind search for HI and OH absorption lines towards mid-infrared color selected radio-loud AGNs
• New constraints on the physical conditions in H${}_2$-bearing GRB-host damped Lyman-$\alpha$ absorbers
• Hunting for Metals Using XQ-100 Legacy Survey Composite Spectra
• Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models
• The nature of H{\sc i}-absorption-selected galaxies at $z\approx 4$
• Gaia-assisted selection of a quasar reddened by dust in an extremely-strong Damped Lyman-α Absorber at z=2.226
• On the dust properties of high redshift molecular clouds and the connection to the 2175 Å extinction bump
• Determining the fraction of reddened quasars in COSMOS with multiple selection techniques from X-ray to radio wavelengths
• Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2
• Extent and structure of intervening absorbers from absorption lines redshifted on quasar emission lines
• A survey of Ly$\alpha$ emission around Damped Ly$\alpha$ absorbers at $z\approx 2$ with the Keck Cosmic Web Imager
• Proximate molecular quasar absorbers: Chemical enrichment and kinematics of the neutral gas
• A Spatially-Resolved Survey of Distant Quasar Host Galaxies: II. Photoionization and Kinematics of the ISM
• Modeling the Statistics of the Cold Neutral Medium in Absorption-selected High-redshift Galaxies
• A Massive, Dusty HI-Absorption-Selected Galaxy at $z\approx 2.46$ Identified in a CO Emission Survey
• Exploring galaxy dark matter halos across redshifts with strong quasar absorbers
• The galaxy counterpart and environment of the dusty Damped Lyman-alpha Absorber at z=2.226 towards Q1218+0832
• DLA and sub-DLA metallicity evolution: A case study of absorbers towards Q0338-0005
• Extremely strong DLAs at high redshift: Gas cooling and H${}_2$ formation
• Past, Present and Future of UHECR Observations
• On the Dusty Proximate Damped Lyman-α System toward Q2310-3358 at z = 2.40
• Detecting PAHs in high-z galaxies in proxy: Modelling physical conditions in an extremely strong damped Lyman-alpha absorber towards QSO SDSS J1143+1420 at z=2.323