The SDSS Damped Lyα Survey: Data Release 3

By J. Xavier Prochaska, S. Herbert-Fort, A. Wolfe. 2005

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We present the results from a damped Lyα survey of the Sloan Digital Sky Survey, Data Release 3. We have discovered over 500 new damped Lyα systems at z > 2.2, and the complete statistical sample for z > 1.6 has more than 600 damped Lyα galaxies. We measure the H I column density distribution fH i(N, X) and its zeroth and first moments (the incidence ℓDLA and gas mass density Ω of damped Lyα systems, respectively) as a function of redshift. The key results include: (1) the full SDSS DR3 fH i(N, X) distribution (z ~ 3.06) is well fit by a Γ function (or double power law) with "break" column density Nγ = 1021.5±0.1 cm-2 and "faint-end" slope α = -1.8 ± 0.1; (2) the shape of the fH i(N, X) distributions in a series of redshift bins does not show evolution; (3) the incidence and gas mass density of damped systems decrease by 35% ± 9% and 50% ± 10% during ≈1 Gyr between the redshift intervals z = [3.0, 3.5] and z = [2.2, 2.5]; and (4) the incidence and gas mass density of damped Lyα systems in the lowest SDSS redshift bin (z = 2.2) are consistent with the current values. We investigate a number of systematic errors in damped Lyα analysis and identify only one important effect: we measure 40% ± 20% higher Ω values toward a subset of brighter quasars than toward a faint subset. This effect is contrary to the bias associated with dust obscuration and suggests that gravitational lensing may be important. Comparing the results against several models of galaxy formation in ΛCDM, we find that all of the models significantly underpredict ℓDLA at z = 3, and only SPH models with significant feedback can reproduce Ω at high redshift. Based on our results for the damped Lyα systems, we argue that the Lyman limit systems contribute ≈33% of the universe's H I atoms at all redshifts z = 2-5. Furthermore, we infer that the fH i(N, X) distribution for N < 1020 cm-2 has an inflection with slope d log f/d log N > -1. We advocate a new mass density definition, the mass density of predominantly neutral gas Ω, to be contrasted with the mass density of gas associated with H I atoms. We contend the damped Lyα systems contribute >80% of Ω at all redshifts and therefore are the main reservoirs for star formation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/109f5ec2bcabd10b44534dcf4b1f3ac4dbeba96d

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Citations in the corpus

C, N, O abundances in the most metal-poor damped Lyman alpha systems★ (2007, result): “The four QSOs observed were selected based on the weakness of metal lines in DLAs already known to be present in their spectra, either from the trawl of the SDSS QSO sample by Prochaska et al. (2005) or from earlier published studies.”
METALLICITY EVOLUTION OF DAMPED Lyα SYSTEMS OUT TO z ∼ 5 (2012, methodology): “The first sample of targets were drawn from the SDSS-DR3 and SDSS-DR5 surveys for damped Ly-α systems performed by Prochaska et al. (2005) and Prochaska & Wolfe (2009) respectively.”
ON THE (NON)EVOLUTION OF H i GAS IN GALAXIES OVER COSMIC TIME (2008, neutral): “This experiment has been realized over the past few years as an unintended consequence of the Sloan Digital Sky Survey (SDSS) of high redshift quasars (Prochaska & Herbert-Fort 2004; Prochaska et al. 2005, ; hereafter PHW05).”
Absorption-line systems in simulated galaxies fed by cold streams (2011, background): “This column density threshold is in good agreement with the knee in the observed DLA column density distribution (Prochaska et al. 2005; Noterdaeme et al. 2009) that, indeed, is interpreted as the transition between atomic and molecular gas (e.g. Zwaan & Prochaska 2006).”
Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database (2008, methodology): “1 gives the distribution of N(H i) from sample S, sub-samples SH2 and SHF to be compared to the reference distribution derived from the SDSS-DR5 DLA sample scaled to the number of systems in the UVES sample (Prochaska et al. 2005).”
The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density (2013, background): “The line density of quasar absorbers, also termedl(X), is the product of the comoving number density and the cross section of absorbers (see Prochaska et al. 2005).”
Evolution of the cosmological mass density of neutral gas from Sloan Digital Sky Survey II - Data Release 7 (2009, background): “This definition is very similar to that of Prochaska et al. (2005) and guaranties robust detections of DLAs in spectra of minimum SNR. 3347 quasars withz0min > zmax were obviously not considered any further.”
THE EVOLUTION OF LYMAN LIMIT ABSORPTION SYSTEMS TO REDSHIFT SIX (2010, background): “The present data (black squares and 1 σ error bars) show no evolution in ΩDLA to z = 5 (see also Prochaska et al. 2005; Péroux et al. 2005; Noterdaeme et al. 2009; Guimarães et al. 2009).”
Quasars Probing Quasars. I. Optically Thick Absorbers near Luminous Quasars (2006, background): “This profile was fitted with a similar value by Prochaska et al. (2005) but not included in their sample because of the low S/N.”
The Neutral Hydrogen Cosmological Mass Density at z = 5 (2015, methodology): “…recent DLA surveys at 2 < z < 4 using more than 10,000 QSOs assembled from the Sloan Digital Sky Survey (SDSS) (Prochaska & Herbert-Fort 2004; Prochaska et al. 2005; Prochaska & Wolfe 2009; Noterdaeme et al. 2009, 2012) have shown that there is very little evolution in the H I mass density…”
Probing the Interstellar Medium near Star-forming Regions with Gamma-Ray Burst Afterglow Spectroscopy: Gas, Metals, and Dust (2007, background): “…promoting the loss of angular momentum (Vink & de Koter 2005), Langer & Norman (2006) and Woosley & Heger (2006) have argued that GRB pro- 6We note that the few GRB sightlines with NHI < 10 20 cm−2 have very low column densities for low-ion transitions (Fiore et al. 2005; Prochaska et al. 2005).”
Column density distribution and cosmological mass density of neutral gas: Sloan Digital Sky Survey-III Data Release 9 (2012, background): “…via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/L1 The most recent contributions to the census of DLAs have used data mining of thousands of quasar spectra from the SDSS (SDSS, York et al. 2000) by Prochaska et al. (2005), Prochaska et al. (2009), and Noterdaeme et al. (2009, hereafter N09).”
Damped Lyman α systems in galaxy formation simulations (2008, background): “Prochaska et al. (2005) discussed how different assumptions for the functional form of the column density distribution can leadto different values ofΩDLA.”
The HI content of star-forming galaxies at z = 0.24 (2007, background): “However, the damped Lyα measurements of Prochaska et al. (2005) only indicate that the neutral gas density rises by factor of ∼2.”
Measurement of BAO correlations at $z=2.3$ with SDSS DR12 \lya-Forests (2017, methodology): “The neutral-hydrogen column densities were drawn randomly with NHI > 1017.2 cm−2, assuming an intrinsic power-law distribution corrected for self-shielding and normalized to match the observations of Prochaska et al. (2005).”