Metal abundances at z &lt; 1.5: new measurements in sub-damped Lyman α absorbers

Péroux, Céline; Meiring, Joseph D.; Kulkarni, Varsha P.; Khare, Pushpa; Lauroesch, J. T.; Vladilo, G.; York, Donald G.

doi:10.1111/j.1365-2966.2008.13186.x

Cited by 55 publications

(54 citation statements)

References 69 publications

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“…We find that N v [α/H] 6 . Although it is tempting to interpret this as evidence that sub-DLAs represent a fundamentally different category of absorber than DLAs (indeed, many studies have found sub-DLAs have higher mean metallicities; Péroux et al 2007Péroux et al , 2008Kulkarni et al 2007;Meiring et al 2007Meiring et al , 2008, we cannot rule out the possibility that in these two cases, we are seeing ionization effects. Indeed, this would cause the sub-DLA [N/H] and [N/α] to be underestimated and [α/H] to be overestimated.…”

Section: Resultsmentioning

confidence: 86%

Metal-enriched plasma in protogalactic halos

Fox¹,

Prochaska

Ledoux³

et al. 2009

A&A

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We continue our recent work of characterizing the plasma content of high-redshift damped and sub-damped Lyman-α systems (DLAs/sub-DLAs), which represent multi-phase gaseous (proto)galactic disks and halos seen toward a background source. We survey N v absorption in a sample of 91 DLAs and 18 sub-DLAs in the redshift range 1.67 < z abs < 4.28 with unblended coverage of the N v doublet. Our dataset includes high-resolution (6−8 km s are required to keep the cloud sizes physically reasonable. The nature of the remaining ≈80% of (broad) N v components is unclear; models of radiatively-cooling collisionally-ionized plasma at log (T /K) = 5.2−5.4 are fairly successful in reproducing the observed integrated high-ion column density ratios and the component line widths, but we cannot rule out photoionization by local sources.Finally, we identify several unusual DLAs with extremely low metallicity (<0.01 solar) but strong high-ion absorption (log N(N v) > 14 or log N(O vi) > 14.2), which present challenges to either galactic inflow or outflow models.

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Section: Resultsmentioning

confidence: 86%

Metal-enriched plasma in protogalactic halos

Fox¹,

Prochaska

Ledoux³

et al. 2009

A&A

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“…Since the discovery of the metal-rich absorber toward SDSSJ1323-0021, several more absorbers (primarily subDLAs) with solar or supersolar metallicities have been found in other recent studies (e.g., Prochaska et al 2006;Kulkarni et al 2007Kulkarni et al , 2009Péroux et al 2008;Meiring et al 2009b, and references therein). In the future, systematic high spatial resolution imaging of more quasar fields with absorbers of known metallicities will be critical for understanding how the stellar populations of metal-rich and metal-poor galaxies differ.…”

Section: Discussionmentioning

confidence: 99%

Adaptive Optics Imaging of a Massive Galaxy Associated With a Metal-Rich Absorber

Chun

Kulkarni

Gharanfoli

et al. 2009

The Astronomical Journal

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The damped and sub-damped Lyα absorption (DLA and sub-DLA) line systems in quasar spectra are believed to be produced by intervening galaxies. However, the connection of quasar absorbers to galaxies is not wellunderstood, since attempts to image the absorbing galaxies have often failed. While most DLAs appear to be metal poor, a population of metal-rich absorbers, mostly sub-DLAs, has been discovered in recent studies. Here we report high-resolution K-band imaging with the Keck laser guide star adaptive optics (LGSAO) system of the field of quasar SDSSJ1323-0021 in search of the galaxy producing the z = 0.72 sub-DLA absorber. With a metallicity of 2-4 times the solar level, this absorber is one of the most metal-rich systems found to date. Our data show a large bright galaxy with an angular separation of only 1. 25 from the quasar, well-resolved from the quasar at the high resolution of our data. The galaxy has a magnitude of K = 17.6-17.9, which corresponds to a luminosity of ≈3-6 L * . Morphologically, the galaxy is fitted with a model with an effective radius, enclosing half of the total light, of R e = 4 kpc and a bulge-to-total ratio of 0.4-1.0, indicating a substantial bulge stellar population. Based on the mass-metallicity relation of nearby galaxies, the absorber galaxy appears to have a stellar mass of 10 11 M . Given the small impact parameter (9.0 kpc at the absorber redshift), this massive galaxy appears to be responsible for the metal-rich sub-DLA. The absorber galaxy is consistent with the metallicityluminosity relation observed for nearby galaxies, but is near the upper end of metallicity. Our study marks the first application of LGSAO for the study of the structure of galaxies producing distant quasar absorbers. Finally, this study offers the first example of a massive galaxy with a substantial bulge producing a metal-rich absorber.

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“…These results appear to contradict the near-solar mass-weighted mean metallicity at ∼ z 0 predicted by most models and observed in nearby galaxies. Equally surprising, a significant fraction of sub-DLAs appear to be highly metal-rich (near-solar or supersolar), even at redshifts of > z 2 (e.g., Akerman et al 2005;Péroux et al 2006aPéroux et al , 2006bPéroux et al , 2008Prochaska et al 2006;Meiring et al 2007Meiring et al , 2008Meiring et al , 2009aMeiring et al , 2009bKulkarni et al 2007Kulkarni et al , 2010Nestor et al 2008;Som et al 2013Som et al , 2015. The supersolar metallicities observed in many sub-DLAs (a large fraction of which are derived from Zn) are particularly strikingbecause no local counterparts to such systems are known among normal galaxies.…”

Section: Application To Dlas and Sub-dlasmentioning

confidence: 99%

“…The abundances of these elements provide very sensitive indicators of the chemical evolution of galaxies (e.g., Pettini et al 1997;Kulkarni & Fall 2002;Prochaska et al 2003;Péroux et al 2008;Meiring et al 2009b;Cooke et al 2011;Rafelski et al 2012;Som et al 2013Som et al , 2015. Because different elements are produced by stars of different masses, the measurements of element abundances as a function of time give information about the history of the formation of stars of different masses in galaxies.…”

Section: Introductionmentioning

confidence: 99%

Atomic Data for Zn Ii: Improving Spectral Diagnostics of Chemical Evolution in High-Redshift Galaxies

Kisielius

Kulkarni

Ferland

et al. 2015

ApJ

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Damped Lyα (DLA) and sub-DLA absorbers in quasar spectra provide the most sensitive tools for measuring the element abundances of distant galaxies. The estimation of abundances from absorption lines depends sensitively on the accuracy of the atomic data used. We have started a project to produce new atomic spectroscopic parameters for optical andUV spectral lines using state-of-the-art computer codes employing a very broad configuration interaction (CI) basis. Here we report our results for Zn II, an ion used widely in studies of the interstellar medium (ISM) as well as DLAs andsub-DLAs. We report new calculations of many energy levels of Zn IIand the line strengths of the resulting radiative transitions. Our calculations use the CI approach within a numerical HartreeFock framework. We use both nonrelativistic and quasi-relativistic one-electron radial orbitals. We have incorporated the results of these atomic calculations into the plasma simulation code Cloudyand applied them to a lab plasma and examples of a DLA and a sub-DLA. Our values of the Zn II λλ 2026, 2062 oscillator strengths are higher than previous values by 0.10 dex. TheCloudy calculations for representative absorbers with the revised Zn atomic data imply ionization corrections lower than calculated earlier by 0.05 dex. The new results imply that Zn metallicities should be lower by 0.1 dex for DLAs and by 0.13-0.15 dex for sub-DLAs than in past studies. Our results can be applied to other studies of Zn II in the Galactic and extragalactic ISM.

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Metal abundances at z < 1.5: new measurements in sub-damped Lyman α absorbers

Cited by 55 publications

References 69 publications

Metal-enriched plasma in protogalactic halos

Metal-enriched plasma in protogalactic halos

Adaptive Optics Imaging of a Massive Galaxy Associated With a Metal-Rich Absorber

Atomic Data for Zn Ii: Improving Spectral Diagnostics of Chemical Evolution in High-Redshift Galaxies

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