Zinc as a tracer of metallicity evolution of Damped Lyman alpha systems

Abstract

Zinc is a good indicator of metallicity in Damped Lyman alpha (DLA) systems because it is almost unaffected by dust depletion. However, the use of zinc as a tracer of metallicity evolution has been hampered by the difficulty of detecting the Zn II resonance lines at high redshift. The measurement of zinc abundance in a DLA system at z_abs > 3 obtained by means of the UVES spectrograph at the VLT prompted us to re-analyse the full sample of zinc abundances present in the literature to search for a metallicity-redshift relation in DLA systems. The study of the metallicities of individual systems shows evidence for an anti-correlation between [Zn/H] and redshift supported by different types of statistical tools. The zinc metallicity decreases by -0.3 +/- 0.1 dex per unit redshift interval in the range 0.5 <~ z_abs <~ 3.5. This rate is in good agreement with that found by Savaglio, Panagia & Stiavelli (2000) in their recent study of DLA abundances corrected for dust depletion. The present result does not require a knowledge of the dust depletion pattern(s) in DLA systems. On the other hand, the analysis of the column-density weighted metallicity of the sample, <Z>, does not show a clear evidence for redshift evolution, consistent with previous studies of zinc abundances. We propose that the apparent lack of evolution of <Z> is due to the combination of selection bias effects together with the extreme sensitivity of <Z> to low-number statistics.

arXiv commentTo appear in Astrophysical Journal. 7 pages, 2 figures

References in corpus (13)

• Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter
• Abundances at High Redshifts: the Chemical Enrichment History of Damped Lyman-alpha Galaxies
• The Metallicity of High Redshift Galaxies: The Abundance of Zinc in 34 Damped Lyman Alpha Systems from z = 0.7 to 3.4
• Metal Abundances at z < 1.5: Fresh Clues to the Chemical Enrichment History of Damped Lyman alpha Systems
• Chemical Abundances of the Damped Lya Systems at z>1.5
• Si and Mn Abundances in Damped Lya Systems with Low Dust Content
• Dust and elemental abundances in Damped Ly alpha absorbers
• A Keck HIRES Investigation of the Metal Abundances and Kinematics of Three Damped Lya Systems Toward Q2206-199
• A Keck HIRES Investigation of the Metal Abundances and Kinematics of the z=2.46 Damped Lya System Toward Q0201+365
• UVES observations of QSO 0000-2620: oxygen and zinc abundances in the Damped Ly-alpha galaxy at z_abs=3.3901
• First Comparison of Ionization and Metallicity in Two Lines of Sight Toward HE 1104-1805 AB at z=1.66
• Discovery of z=0.0912 and z=0.2212 Damped Lyman-alpha Absorption Line Systems Toward the Quasar OI 363: Limits on the Nature of Damped Lyman-alpha Galaxies
• On the origin of Damped Lyman-alpha systems: a case for LSB galaxies?

Cited by in corpus (32)

• Damped Lyman alpha Systems
• The extreme r-element rich, iron-poor halo giant CS31082-001: Implications for the r-process site(s) and radioactive cosmochronology
• The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems
• Molecular hydrogen, deuterium and metal abundances in the damped Ly-alpha system at z = 3.025 toward QSO 0347-3819
• Hubble Space Telescope Observations of Element Abundances in Low-redshift Damped Lyman-alpha Galaxies and Implications for the Global Metallicity-Redshift Relation
• Implications of Cosmological Gamma-Ray Absorption - I.Evolution of the Metagalactic Radiation Field
• Ionization Properties and Elemental Abundances in Damped Ly alpha Systems
• A Homogeneous Sample of Sub-DLAs I: Construction of the Sample and Chemical Abundance Measurements
• A Homogeneous Sample of Sub-DLAs II: Statistical, Kinematic and Chemical Properties
• The missing metals problem. III How many metals are expelled from galaxies?
• Metals and Dust in Intermediate-redshift Damped Ly-alpha Galaxies
• Chemical evolution and nature of Damped Lyman-Alpha systems
• UVES observations of QSO 0000-2620: Argon and Phosphorus abundances in the dust-free damped Ly-alpha system at zabs = 3.3901
• The Magellan Uniform Survey of Damped Lyman alpha Systems I: Cosmic Metallicity Evolution
• Metal abundances and ionization conditions in a possibly dust-free damped Ly-alpha system at z=2.3
• Metallicity Evolution of Damped Lyman-Alpha Galaxies
• Chemical Evolution of Damped Ly alpha galaxies: The [S/Zn] abundance ratio at redshift z > 2
• Cosmic metal production and the mean metallicity of the Universe
• Two-phase equilibrium and molecular hydrogen formation in damped Lyman-alpha systems
• A scaling law for interstellar depletions
• MusE GAs FLOw and Wind (MEGAFLOW) V. The dust/metallicity-anisotropy of the Circum-Galactic Medium
• Relationships between the HI 21-cm line strength, MgII equivalent width and metallicity in damped Lyman-alpha absorption systems
• High-resolution O VI absorption line observations at 1.2 < z < 1.7 in the bright QSO HE 0515-4414
• Ar I as a tracer of ionization evolution
• A new measurement of zinc metallicity in a DLA at z=3.35
• Cosmic metal density evolution in neutral gas: insights from observations and cosmological simulations
• Cosmological Evolution of Heavy Element and Molecular Hydrogen Abundances
• Classical and MgII-selected Damped Lyman-alpha Absorbers: impact on Omega_HI at z<1.7
• Chemical Enrichment in Damped Lyman Alpha Systems From Hierarchical Galaxy Formation Models
• Chemical Enrichment at High Redshifts: Understanding the Nature of Damped Ly$\alpha$ Systems in Hierarchical Models
• Building Blocks in Hierarchical Clustering Scenarios and their Connection with Damped Ly$\alpha$ Systems
• Extremely strong DLAs at high redshift: Gas cooling and H${}_2$ formation