On the selection of damped Lyman alpha systems using MgII absorption at 2<z<4

Abstract

The XQ-100 survey provides optical and near infrared coverage of 36 blindly selected, intervening damped Lyman alpha systems (DLAs) at 2 < z < 4, simultaneously covering the MgII doublet at 2796A, 2803A, and the Ly-alpha transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their MgII rest-frame equivalent width (W2796) at these redshifts. Of the 29 DLAs with clean MgII profiles, we find that six (20% of DLAs) have W2796 < 0.6A. The DLA incidence rate of W2796 < 0.6A absorbers is a factor of ~5 higher than what is seen in z~1 samples, indicating a potential evolution in the MgII properties of DLAs with redshift. All of the W2796 < 0.6A DLAs have low metallicities (-2.5 < [M/H] < -1.7), small velocity widths (v90 < 50 km/s), and tend to have relatively low N(HI). We demonstrate that the exclusion of these low W2796 DLAs results in a higher mean N(HI) which in turn leads to a ~7% increase in the cosmological gas density of HI of DLAs at 2 < z < 4; and that this exclusion has a minimal effect on the HI-weighted mean metallicity.

arXiv commentAccepted into MNRAS Letters. 6 pages, 2 figures

References in corpus (36)

• Damped Lyman alpha Systems
• The HIPASS catalogue: Omega_HI and environmental effects on the HI mass function of galaxies
• Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample
• The SDSS Damped Lya Survey: Data Release 3
• On the Kinematics of the Damped Lyman Alpha Protogalaxies
• Column density distribution and cosmological mass density of neutral gas: Sloan Digital Sky Survey-III Data Release 9
• On the (Non)Evolution of HI Disks over Cosmic Time
• Metallicity Evolution of Damped Lyman-alpha Systems out to z~5
• The Arecibo Legacy Fast ALFA Survey: X. The HI Mass Function and Omega_HI From the 40% ALFALFA Survey
• Damped Lyman alpha absorbers at high redshift -- large disks or galactic building blocks?
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• Velocity-Metallicity Correlation for high-z DLA Galaxies: Evidence for a Mass-Metallicity Relation?
• Surveys for z > 3 Damped Lyman-alpha Absorption Systems
• The evolution of Omega(HI) and the epoch of formation of damped Lyman-alpha absorbers
• Metal Abundances at z < 1.5: Fresh Clues to the Chemical Enrichment History of Damped Lyman alpha Systems
• The Neutral Hydrogen Cosmological Mass Density at z=5
• The ESO UVES Advanced Data Products Quasar Sample - II. Cosmological Evolution of the Neutral Gas Mass Density
• The Rapid Decline in Metallicity of Damped Ly-alpha Systems at z~5
• Mass-metallicity relation from z=5 to the present: Evidence for a transition in the mode of galaxy growth at z=2.6 due to the end of sustained primordial gas infall
• The Fundamental Plane of Damped Lyman Alpha Systems
• Verifying the mass-metallicity relation in damped Lyman-alpha selected galaxies at 0.1<z<3.2
• The HI Content of the Universe over the Past 10 Gyrs
• The Role of Sub-damped Lyman-alpha Absorbers in the Cosmic Evolution of Metals
• The evolution of neutral gas in damped Lyman $\alpha$ systems from the XQ-100 survey
• The nature of proximate damped Lyman alpha systems
• Understanding Physical Conditions in High Redshift Galaxies through C I Fine Structure Lines: Data and Methodology
• The CORALS Survey II: Clues to Galaxy Clustering Around QSOs from z_abs ~ z_em Damped Lyman Alpha Systems
• An efficient technique for pre-selecting low redshift damped Lyman alpha systems
• The connection between metallicity and metal-line kinematics in (sub-)damped Lyman-alpha systems
• GMRT observation of neutral atomic hydrogen gas in the COSMOS field at $z\sim 0.37$
• Damped Lyman Alpha Gas Metallicities at Redshifts z=0.9-2.0 from SDSS Spectra
• The chemistry of the most metal-rich damped Lyman $\alpha$ systems at z$\sim 2$ II. Context with the Local Group
• Chemical abundances of damped Lyman alpha systems in the XQ-100 survey
• Revisiting the origin of the high metallicities of sub-damped Lyman-alpha systems
• Classical and MgII-selected Damped Lyman-alpha Absorbers: impact on Omega_HI at z<1.7
• The kinematic signature of damped Lyman alpha systems: Using the D-index to screen for high column density HI absorbers

Cited by in corpus (17)

• Neutral hydrogen (HI) gas content of galaxies at $z\approx 0.32$
• The Statistical Properties of Neutral Gas at z<1.65 from UV Measurements of Damped Lyman Alpha Systems
• FLASH Early Science -- Discovery of an intervening HI 21-cm absorber from an ASKAP survey of the GAMA 23 field
• Stellar masses, metallicity gradients and suppressed star formation revealed in a new sample of absorption selected galaxies
• A successful search for intervening 21 cm HI absorption in galaxies at 0.4 < z <1.0 with the Australian Square Kilometre Array Pathfinder (ASKAP)
• The evolution of neutral hydrogen over the past 11 Gyr via HI 21 cm absorption
• Evidence of First Stars-enriched Gas in High-redshift Absorbers
• Strong Mg II and Fe II Absorbers at 2.2 < z < 6.0
• Sub-damped Lyman alpha systems in the XQ-100 survey I -- Identification and contribution to the cosmological HI budget
• Sub-damped Lyman alpha systems in the XQ-100 survey II -- Chemical evolution at 2.4<z<4.3
• Hunting for Metals Using XQ-100 Legacy Survey Composite Spectra
• Solving the conundrum of intervening strong MgII absorbers towards GRBs and quasars
• The distribution and properties of DLAs at z $\le$ 2 in the EAGLE simulations
• Ghostly Damped Ly$\alpha$ Systems: Tracers of Gas Flows in the Close Vicinity of Quasars ?
• MUSE-ALMA Haloes IX: Morphologies and Stellar Properties of Gas-rich Galaxies
• The Qz5 Survey (I): How the HI Mass Density of the Universe Evolves With Cosmic Time
• Ultra-strong MgII absorbers trace both inflowing and outflowing gas: insights from dual down-the-barrel and quasar sightlines