The Evolution of Lyman alpha Absorbers in the Redshift Range 0.5<z<1.9

Abstract

We investigate the evolution and the statistical properties of the Lya absorbers of the intergalactic medium (IGM) in the largely unexplored redshift range z=0.5-1.9. We use high-resolution (R > 30,000) UV (STIS) and optical (VLT/UVES and Keck/HIRES) spectra of nine bright quasars with z_em < 1.94. The main results for the combined Lya line sample are summarized as follows: 1. The evolution of the number density of the absorbers can be described by the power law dn/dz ~ (1+z)^gamma. The number density of the low column density lines decreases with decreasing z with gamma=0.74+-0.31 in the interval z=0.7-1.9. A comparison with results at higher redshifts shows that it is decelerated in the explored redshift range and turns into a flat evolution for z -> 0. The stronger absorbers thin out faster (gamma=1.50+-0.45). The break in their evolution predicted for z=1.5-1.7 cannot be seen down to z=0.7. On the other hand, a comparison with values from the literature for the local number density gives a hint that this break occurs at lower redshift. 2. The distribution of the column densities of the absorbers is complete down to N_HI=10^12.90 cm^-2. It can be approximated by a single power law with the exponent beta=1.60+-0.03 over almost three orders of magnitude. beta is redshift independent. 3. The Lya lines with lower column densities as well as the higher column density lines show marginal clustering with a 2 sigma significance over short distances (Delta v < 200 km/s and Delta v < 100 km/s, respectively). We do not see any difference in the clustering with either column density or redshift.

arXiv comment15 pages, 18 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (30)

• Radiative Transfer in a Clumpy Universe: II. The Utraviolet Extragalactic Background
• The Rest-Frame Extreme Ultraviolet Spectral Properties of QSOs
• The Low Redshift Lyman Alpha Forest in Cold Dark Matter Cosmologies
• The Distribution of Column Densities and b Values in the Lyman-Alpha Forest
• The Local Ly-alpha Forest IV: STIS G140M Spectra and Results on the Distribution and Baryon Content of HI Absorbers
• Probing the variability of the fine-structure constant with the VLT/UVES
• Intrinsic Properties of the <z>=2.7 Lyman Alpha Forest from Keck Spectra of QSO HS 1946+7658
• The HST Quasar Absorption Line Key Project. XIV. The Evolution of Ly-alpha Absorption Lines in the Redshift Interval 0 to 1.5
• The physical properties of the Ly-Alpha forest at z > 1.5
• The Redshift Evolution of the Lyman Alpha Forest
• The Lyman-Alpha Forest at 1.5 < z < 4
• The Local Lyman-alpha Forest. II: Distribution of HI Absorbers, Doppler Widths, and Baryon Content
• Cosmological parameters sigma_8, the baryon density, and the UV background intensity from a calibrated measurement of H I Lyman-alpha absorption at z = 1.9
• The H I opacity of the intergalactic medium at redshifts 1.6 < z < 3.2
• The Statistical and Physical Properties of the Low Redshift Lyman Alpha Forest Observed with HST/STIS
• Low-redshift evolution of the Lyman-alpha Forest
• The Space Distribution of the Lyman Alpha Clouds in the Line of Sight to the Z=3.66 QSO 0055-269
• A Concordance Model of the Lyman-alpha Forest at z = 1.95
• The b Distribution and the Velocity Structure of Absorption Peaks in the Lyman-Alpha Forest
• Detection of molecular hydrogen at z=1.15 toward HE 0515-4414
• A Study of Lyman-Alpha Quasar Absorbers in the Nearby Universe
• The Lyman-alpha forest of the QSO in the Hubble Deep Field South
• Strong Clustering in the Low Redshift Lyman-$\alpha$ Forest
• Photoionized OVI absorbers toward the bright QSO HE 0515-4414
• High-resolution O VI absorption line observations at 1.2 < z < 1.7 in the bright QSO HE 0515-4414
• Fine-structure diagnostics of neutral carbon toward HE 0515-4414
• HE 0141-3932: a bright QSO with an unusual emission line spectrum and associated absorption
• Spectral shape of the UV ionizing background and OVI absorbers at z ~ 1.5 towards HS0747+4259
• A uniform analysis of the Lyman alpha forest at z = 0-5: IV. The clustering and evolution of clouds at z < 1.7
• A high-resolution study of the evolution of the Lyman alpha forest in the redshift interval 0.9 < z < 1.7

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