Metals and Dust in Intermediate‐Redshift Damped Lyα Galaxies

Khare, Pushpa; Kulkarni, Varsha P.; Lauroesch, J. T.; York, Donald G.; Crotts, Arlin; Nakamura, Osamu

doi:10.1086/424893

Cited by 79 publications

(153 citation statements)

References 94 publications

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“…Several works have suggested a decrease of metallicity with hydrogen column density in DLAs (e.g., Boisse et al 1998;Kulkarni & Fall 2002;Khare et al 2004;Akerman et al 2005;Meiring et al 2006), which could also extend to sub-DLAs (Péroux et al 2003a;DessaugesZavadsky et al 2003;York et al 2006;Kulkarni et al 2007;Khare et al 2007;Som et al 2013Som et al , 2015Kulkarni et al 2015). As seen in Figure 14, the value of σ h and the derived metal column densities are anticorrelated.…”

Section: Modelling Blended Linesmentioning

confidence: 62%

“…Sometimes a single component with a narrow velocity width close to the thermal value for photoionized gas clouds is observed, but often several components are seen over a typical velocity range ∼ 100 − 300 km s −1 (Prochaska & Wolfe 1997;Zwaan et al 2008). The derived metallicities are generally low, distributed over a broad range of 10 −3 to 10 −1 Z (Prochaska & Wolfe 2002;Prochaska et al 2003b;Kulkarni et al 2005; Ledoux et al 2006), and on average declining with redshift (Kulkarni & Fall 2002;Vladilo 2002;Prochaska et al 2003a;Calura et al 2003;Khare et al 2004;Akerman et al 2005;Kulkarni et al 2005;Rafelski et al 2012;Jorgenson et al 2013; arXiv:1610.02711v2 [astro-ph.GA] 17 Jul 2017 Neeleman et al 2013;Møller et al 2013;Rafelski et al 2014;Quiret et al 2016). The complex velocity profiles suggest a highly turbulent environment, and models of clouds moving in random orbits in galactic halos or thick disks can generally explain the observations (Haehnelt et al 1998;Fumagalli et al 2011;Cen 2012;Rahmati & Schaye 2014;Barnes & Haehnelt 2014;Bird et al 2015;Neeleman et al 2015, but see also York et al 1986).…”

Section: Introductionmentioning

confidence: 99%

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The Mean Metal-line Absorption Spectrum of Damped Lyα Systems in BOSS

Mas-Ribas

Miralda-Escudé

Pérez-Ràfols

et al. 2017

ApJ

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We study the mean absorption spectrum of the Damped Lyman alpha population at z ∼ 2.6 by stacking normalized, rest-frame shifted spectra of ∼ 27 000 DLAs from the DR12 of BOSS/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column density, 5 intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with N HI , whereas for high-ionization lines the increase is much weaker. The mean metal line equivalent widths decrease by a factor ∼ 1.1 − 1.5 from z ∼ 2.1 to z ∼ 3.5, with small or no differences between low-and high-ionization species. We develop a theoretical model, inspired by the presence of multiple absorption components observed in high-resolution spectra, to infer mean metal column densities from the equivalent widths of partially saturated metal lines. We apply this model to 14 low-ionization species and to AlIII, SIII, SiIII, CIV, SiIV, NV and OVI. We use an approximate derivation for separating the equivalent width contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species NI, ZnII, CII * , FeIII, and SIV. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.

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Section: Modelling Blended Linesmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

The Mean Metal-line Absorption Spectrum of Damped Lyα Systems in BOSS

Mas-Ribas

Miralda-Escudé

Pérez-Ràfols

et al. 2017

ApJ

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“…In addition we determine the redshift at which the system has its largest optical depth, zτ:max = 0.71625. (obtained by Khare et al 2004). We note that the identification of the absorber as a DLA or a sub-DLA and the value of the metallicity is critically dependent on the HI column density estimate.…”

Section: Vlt Uves and Hst Stis Datamentioning

confidence: 96%

ALMA + VLT observations of a damped Lyman-α absorbing galaxy: massive, wide CO emission, gas-rich but with very low SFR

Møller

Christensen

Zwaan

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We are undertaking an ALMA survey of molecular gas in galaxies selected for their strong HI absorption, so-called DLA/sub-DLA galaxies. Here we report CO(2-1) detection from a DLA galaxy at z = 0.716. We also present optical and near-infrared spectra of the galaxy revealing [OII], Hα and [NII] emission lines shifted by ∼ 170 km s −1 relative to the DLA, and providing an oxygen abundance 3.2 times solar, similar to the absorption metallicity. We report low unobscured SFR∼ 1 M ⊙ yr −1 given the large reservoir of molecular gas, and also modest obscured SFR= 4.5 . Surprisingly, this HI absorption-selected galaxy has no equivalent objects in CO surveys of flux-selected samples. The galaxy falls off current scaling relations for the SFR to molecular gas mass and CO Tully-Fisher relation. Detailed comparison of kinematical components of the absorbing, ionized and molecular gas, combined with their spatial distribution, suggests that part of the CO gas is both kinematically and spatially de-coupled from the main galaxy. It is thus possible that a major star burst in the past could explain the wide CO profile as well as the low SFR. Support for this also comes from the SED favouring an instantaneous burst of age ≈ 0.5 Gyr. Our survey will establish whether flux-selected surveys of molecular gas are missing a key stage in the evolution of galaxies and their conversion of gas to stars.

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“…We restrict the Ionic Column Densities for FJ0812+32 z ¼ 2:0668 Ionic Column Densities for B1013+0035 z ¼ 3:1040 Ionic Column Densities for J2340À00 z ¼ 2:05452 Ionic Column Densities for Q2342+34 z ¼ 2:90823 summary to optical data (i.e., z abs > 1:6) acquired at spectral resolution R > 5500, i.e., echelle or echellette observations. Although lower resolution observations can give accurate metal abundance measurements for favorable optical depth profiles (e.g., Pettini et al 1994;Khare et al 2004), we prefer to restrict the list to cases in which the optical depth profile is at least partially resolved. In general, the metallicities listed in Table 13 [Zn/H], in that order of preference.…”

Section: Dla Metal Summarymentioning

confidence: 99%

The UCSD/Keck Damped Lyα Abundance Database: A Decade of High‐Resolution Spectroscopy

Prochaska

Wolfe

Howk

et al. 2007

ASTROPHYS J SUPPL S

111

118

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We publish the Keck / HIRES and Keck / ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI spectra along 65 unique sight lines providing abundance measurements on %85 DLA systems. The normalized data can be downloaded from the journal or from our supporting Web site. The database includes all of the sight lines that have been included in our papers on the chemical abundances, kinematics, and metallicities of the damped Ly systems. This data has also been used to argue for variations in the fine-structure constant. We present new chemical abundance measurements for 10 damped Ly systems and a summary table of high-resolution metallicity measurements (including values from the literature) for 153 damped Ly systems at z > 1:6. We caution, however, that this metallicity sample (and all previous ones) is biased to higher N H i values than a random sample.

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Metals and Dust in Intermediate‐Redshift Damped Lyα Galaxies

Cited by 79 publications

References 94 publications

The Mean Metal-line Absorption Spectrum of Damped Lyα Systems in BOSS

The Mean Metal-line Absorption Spectrum of Damped Lyα Systems in BOSS

ALMA + VLT observations of a damped Lyman-α absorbing galaxy: massive, wide CO emission, gas-rich but with very low SFR

The UCSD/Keck Damped Lyα Abundance Database: A Decade of High‐Resolution Spectroscopy

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