Average extinction curves and relative abundances for quasi-stellar object absorption-line systems at 1 ≤zabs < 2

By D. York, P. Khare, D. V. vanden Berk, V. Kulkarni, A. Crotts, J. Lauroesch, Gordon Richards, D. Schneider, D. Welty, Yusra AlSayyad and 14 more. 2006

175 citations recorded by the source corpus.

We have studied a sample of 809 Mg II absorption systems with 1.0 ≤ z abs ≤ 1.86 in the spectra of Sloan Digital Sky Survey quasi-stellar objects (QSOs), with the aim of understanding the nature and abundance of the dust and the chemical abundances in the intervening absorbers. Normalized, composite spectra were derived, for abundance measurements, for the full sample and several subsamples, chosen on the basis of the line strengths and other absorber and QSO properties. Average extinction curves were obtained for the subsamples by comparing their geometric mean spectra with those of matching samples of QSOs without absorbers in their spectra. There is clear evidence for the presence of dust in the intervening absorbers. The 2175-A feature is not present in the extinction curves, for any of the subsamples. The extinction curves are similar to the Small Magellanic Cloud (SMC) extinction curve with a rising ultraviolet (UV) extinction below 2200 A. The absorber rest-frame colour excess, E(B - V), derived from the extinction curves, depends on the absorber properties and ranges from <0.001 to 0.085 for various subsamples. The column densities of Mg II, Al II, Si II, Ca II, Ti II, Cr II, Mn II, Fe II, Co II, Ni II and Zn II do not show such a correspondingly large variation. The overall depletions in the high E(B - V) samples are consistent with those found for individual damped Lyman a systems, the depletion pattern being similar to halo clouds in the Galaxy. Assuming an SMC gas-to-dust ratio, we find a trend of increasing abundance with decreasing extinction; systems with N H1 ∼ 10 20 cm -2 show solar abundance of Zn. The large velocity spread of strong Mg II systems seems to be mimicked by weak lines of other elements. The ionization of the absorbers, in general appears to be low: the ratio of the column densities of Al III to Al II is always less than 1/2. QSOs with absorbers are, in general, at least three times as likely to have highly reddened spectra as compared to QSOs without any absorption systems in their spectra.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/938b6d4a0107bbfb461d434b2ce33fc296f5fe95

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Citations in the corpus

THE SDSS-IV EXTENDED BARYON OSCILLATION SPECTROSCOPIC SURVEY: QUASAR TARGET SELECTION (2015, background): “…rare types of quasars, and precision studies of the quasar luminosity function (e.g. Vanden Berk et al. 2001; Inada et al. 2003; McLure & Dunlop 2004; Hennawi et al. 2006; Richards et al. 2006; York et al. 2006; Netzer & Trakhtenbrot 2007; Kaspi et al. 2007; Shen et al. 2008; Boroson & Lauer 2009).”
LOW-RESOLUTION SPECTRAL TEMPLATES FOR ACTIVE GALACTIC NUCLEI AND GALAXIES FROM 0.03 TO 30 μm (2010, background): “This is based on the observed absence of the Galactic 2175 Å feature of Galactic extinction curves in QSO spectra (e.g., York et al. 2006).”
THE BARYON OSCILLATION SPECTROSCOPIC SURVEY OF SDSS-III (2012, methodology): “This dataset has been used to study the statistics of quasar absorption lines (York et al. 2006) and to confirm correlations with quasars (Wild et al. 2007) as well as foreground galaxies projected along the line of sight (Lundgren et al. 2009).”
The Circumgalactic Medium (2017, methodology): “In a pioneering study, York et al. (2006) stacked a sample of 800 strong Mg II absorbers to find evidence of SMC-like dust reddening.”
Measuring the galaxy–mass and galaxy–dust correlations through magnification and reddening (2009, background): “Recently several authors studied their extinction properties and dust content (Ménard et al. 2005; Khare et al. 2005; York et al. 2006).”
THE SLOAN DIGITAL SKY SURVEY QUASAR CATALOG. V. SEVENTH DATA RELEASE (2010, background): “The distribution of Δ(g − i) near the modal curve is roughly symmetric, but the lower left panel in Figure 5 reveals a significant population of “red” quasars that has no “blue” counterpart (also see Richards et al. 2003 and York et al. 2006).”
The physics of the intergalactic medium (2007, unknown): “…Tytler et al. (1987), Sargent et al. (1988b), Steidel and Sargent (1992), Boisse et al. (1992), Aldcroft et al. (1993), Le Brun et al. (1993), Churchill et al. (1999), Nestor et al. (2005), York et al. (2006), Lynch et al. (2006), Nestor et al. (2006), Fox et al. (2006) and Narayanan et al. (2007).”