Damped and sub-damped Lyman-? absorbers in z > 4 QSOs

Abstract

We present the results of a survey for damped (DLA, log N(H I) > 20.3) and sub-damped Lyman-? systems (19.5 < log N(H I) < 20.3) at z > 2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4 < zem < 6.3. Intermediate resolution (R ? 4300) spectra have been obtained with the Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total of 100 systems with log N(H I) > 19.5 are detected of which 40 systems are damped Lyman-? systems for an absorption length of ?X = 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs. We study the evolution with redshift of the cosmological density of the neutral gas and find, consis- tently with previous studies at similar resolution, that ?DLA,H I decreases at z > 3.5. The overall cosmological evolution of ?HI shows a peak around this redshift. The H I column density distribution for log N(H I) ? 20.3 is ?tted, consistently with previous surveys, with a single power-law of index ? ? -1.8$\pm$0.25. This power-law overpredicts data at the high-end and a second, much steeper, power-law (or a gamma function) is needed. There is a flattening of the function at lower H I column densities with an index of ? ? ?1.4 for the column density range log N(H I) = 19.5?21. The fraction of H I mass in sub-DLAs is of the order of 30%. The H column density distribution does not evolve strongly from z ? 2.5 to z ? 4.5.

References in corpus (7)

• Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample
• The SDSS Damped Lya Survey: Data Release 3
• On the (Non)Evolution of HI Disks over Cosmic Time
• A Homogeneous Sample of Sub-DLAs III: Total Gas Mass Omega_(HI+HeII) at z>2
• The Keck+Magellan Survey for Lyman Limit Absorption I: The Frequency Distribution of Super Lyman Limit Systems
• The density structure around quasars from optical depth statistics
• The chemical compositions of 10 new sub-DLAs and strong Lyman-limit systems at z < 1.5

Cited by in corpus (23)

• The Evolution of the Star-forming Interstellar Medium across Cosmic Time
• Cosmic evolution of the atomic and molecular gas content of galaxies
• The Evolution of Lyman Limit Absorption Systems to Redshift Six
• Evolution of the atomic and molecular gas content of galaxies
• 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 Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space
• GRB 100219A with X-shooter - abundances in a galaxy at z = 4.7
• Evolution of the atomic and molecular gas content of galaxies in dark matter haloes
• H${}_2$-based star formation laws in hierarchical models of galaxy formation
• High-Redshift Metals. II. Probing Reionization Galaxies with Low-Ionization Absorption Lines at Redshift Six
• The evolution of neutral gas in damped Lyman $\alpha$ systems from the XQ-100 survey
• Metallicities, dust and molecular content of a QSO-Damped Lyman-α system reaching log N (H i) = 22: An analog to GRB-DLAs
• The neutral gas content of post-merger galaxies
• The ESO UVES Advanced Data Products Quasar Sample - I. Dataset and New N_HI Measurements of Damped Absorbers
• Detection of emission lines from z ~ 3 DLAs towards the QSO J2358+0149
• Damped Lyα Absorption Systems in Semi-Analytic Models with Multiphase Gas
• Sub-damped Lyman alpha systems in the XQ-100 survey I -- Identification and contribution to the cosmological HI budget
• Observed Faraday Effects in Damped Lyman-Alpha Absorbers and Lyman Limit Systems: The Magnetised Environment of Galactic Building Blocks at Redshift=2
• Dark Matter Fraction in z~1 Star-Forming Galaxies
• The Qz5 Survey (I): How the HI Mass Density of the Universe Evolves With Cosmic Time
• Measuring the HI content of individual galaxies out to the epoch of reionization with [CII]
• NeutralUniverseMachine: Predictions of HI gas in Different Theoretical Models