SIMBAD references

2007ApJ...656..666O - Astrophys. J., 656, 666-679 (2007/February-3)

The Keck+Magellan survey for Lyman limit absorption. I. The frequency distribution of super Lyman limit systems.


Abstract (from CDS):

We present the results of a survey for super Lyman limit systems (SLLSs; defined to be absorbers with 19.0/cm2≤logN_HI_≤20.3/cm2) from a large sample of high-resolution spectra acquired using the Keck and Magellan telescopes. Specifically, we present 47 new SLLSs from 113 QSO sight lines. We focus on the neutral hydrogen frequency distribution f_HI_(N,X) of the SLLS and its moments and compare these results with the Lyα forest and the damped Lyα systems (DLAs; absorbers with logN_HI_≥20.3/cm2). We find that the f_HI_(N,X) of the SLLSs can be reasonably described with a power law of index α=-1.43+0.15–0.16 or -1.19+0.20–0.21depending on whether we set the lower N_HI_ bound for the analysis at 1019.0 or 1019.3/cm2, respectively. The results indicate a flattening in the slope of f_HI_(N,X) between the SLLSs and DLAs. We find little evidence for redshift evolution in the shape of f_HI_(N,X) for the SLLSs over the redshift range of the sample 1.68<z<4.47 and only tentative evidence for evolution in the zeroth moment of f_HI_(N,X), the line density ℓSLLS(X). We introduce the observable distribution function O(N,X) and its moment, which elucidates comparisons of H I absorbers from the Lyα forest through to the DLA. We find that a simple three-parameter function can fit O(N,X) over the range 17.0/cm2≤logN_HI_≤22.0/cm2. We use these results to predict that f_HI_(N,X) must show two additional inflections below the SLLS regime to match the observed f_HI_(N,X) distribution of the Lyα forest. Finally, we demonstrate that SLLSs contribute a minor fraction (~15%) of the universe's hydrogen atoms and, therefore, an even smaller fraction of the mass in predominantly neutral gas.

Abstract Copyright:

Journal keyword(s): Galaxies: Intergalactic Medium - Galaxies: Quasars: Absorption Lines

Nomenclature: Tables 2, 3, 4: [OPB2007] QSO JHHMM+DDMM abs N.NNN N=51.

CDS comments: In table 3, SDSS J0949+0355, J1034+0358, J1307+0422, J1621-0042: too short format for SDSS objects (SDSS, These objects are QSO J0949+0355, QSO J1034+0358, QSO J1307+0422, QSO J1621-0042 in SIMBAD. Tables 2, 3, 4: only the objects with unknown z(abs) are designated as [OPB2007].

Simbad objects: 72

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