Metal abundances and ionization conditions in a possibly dust-free damped
Ly<i>α</i> system at $\mathsf{\vec{z}=2.3}$

López, Sebastián; Reimers, D.; D’Odorico, S.; Prochaska, J. Xavier

doi:10.1051/0004-6361:20020181

Cited by 73 publications

(60 citation statements)

References 52 publications

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“…Prochaska & Wolfe (1996) first studied chemical abundance variations in a single DLA, and showed that the chemical abundances were uniform to within statistical uncertainties. Lopez et al (2002) confirmed this finding from analysis of another DLA using Voigt profile decomposition. Petitjean et al (2002) and Ledoux et al (2002b) showed that the depletion patterns in subcomponents were very similar along DLA profiles except in the components where molecular hydrogen is detected and where depletion is larger.…”

Section: Introductionsupporting

confidence: 78%

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

Rodriguez¹,

Petitjean

Aracil³

et al. 2006

A&A

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We investigated abundance ratios along the profiles of six high-redshift Damped Lyman-α systems, three of them associated with H 2 absorption, and derived optical depths in each velocity pixel. The variations of the pixel abundance ratios were found to be remarkably small and usually smaller than a factor of two within a profile. This result holds even when considering independent sub-clumps in the same system. The depletion factor is significantly enhanced only in those components where H 2 is detected. There is a strong correlation between [Fe/S] and [Si/S] abundances ratios, showing that the abundance ratio patterns are definitely related to the presence of dust. The depletion pattern is usually close to the one seen in the warm halo gas of our Galaxy.

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Section: Introductionsupporting

confidence: 78%

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

Rodriguez¹,

Petitjean

Aracil³

et al. 2006

A&A

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“…Even though DLA galaxies have H i column densities spanning an order of magnitude and metallicities spread over two orders of magnitude, previous studies show that DLAs have similar abundance ratios suggesting that these protogalaxies have common enrichment histories (Prochaska & Wolfe 2002). In the same way, the abundance patterns of DLA "clouds" for a given system also show uniformity suggesting that the gas of these protogalaxies has a similar enrichment history and uniform differential dust depletion (Prochaska & Wolfe 1996;Lopez et al 2002;Prochaska 2003). If confirmed, these results have important implications for the ISM of high redshift galaxies and the enrichment of gas in the early Universe.…”

Section: Introductionmentioning

confidence: 67%

“…They compared ionic column densities along the observed velocity profile using the apparent optical depth method (Savage & Sembach 1991). Then, Lopez et al (2002) were the first to present a detailed cloud-to-cloud analysis for a z > 2 damped system based on a Voigt profile analysis.…”

Section: Cloud-to-cloud Chemical Variations In Individualmentioning

confidence: 99%

A new comprehensive set of elemental abundances in DLAs

Dessauges‐Zavadsky¹,

Prochaska

D’Odorico

et al. 2005

A&A

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We present new, comprehensive sets of elemental abundances for seven damped Lyα systems (DLAs) in the redshift range z abs = 1.8−2.5. These were derived from UVES/VLT spectra combined with existing HIRES/Keck spectra. We detected 54 metal-line transitions, and obtained the column density measurements of 30 ions from 22 elements, − B, C, N, O, Mg, Al, Si, P, S, Cl, Ar, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Kr. Together with the four DLAs analyzed in Dessauges-Zavadsky et al. (2004, A&A, 416, 79), we have a sample of eleven DLA galaxies with uniquely comprehensive and homogeneous abundance measurements. These observations allow one to study in detail the abundance patterns of a wide range of elements and the chemical variations in the interstellar medium of galaxies outside the Local Group. Comparing the gas-phase abundance ratios of these high redshift galaxies, we found that they show low rms dispersions, reaching only up 2-3 times the statistical errors for the majority of elements. This uniformity is remarkable given that the quasar sightlines cross gaseous regions with H i column densities spanning over one order of magnitude and metallicities ranging from 1/55 to 1/5 solar. The uniformity is also remarkable since DLAs are expected (and observed at low redshift) to be associated with a wide range of galaxy types. This implies the respective star formation histories seem to have conspired to yield one set of relative abundances. We examined the gas-phase abundance patterns of interstellar medium "clouds" within the DLA galaxies detected along the velocity profiles. By considering all the clouds of all the DLAs studied together, we observe a high dispersion in several abundance ratios, indicating that chemical variations seem to be more confined to individual clouds within the DLA galaxies than to integrated profiles. We found unambiguous correlations between [Si/Fe] The sources of these variations are both the differential dust depletion and/or ionization effects; however, no evidence for variations due to different star formation histories could be highlighted. These observations place large constraints on the mixing timescales of protogalaxies and on scenarios of galaxy formation within the CDM hierarchical theory. Finally, we provide an astrophysical determination of the oscillator strength of the Ni ii λ 1317 transition.

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“…Another place we might look for significant gas-phase H 2 formation is in damped Ly (DLA) systems, many of which have low dust abundances (see, e.g., Lopez et al 2002). An interesting example is the absorber at z ¼ 3:025 in the spectrum of Q0347À3819 recently studied by Levshakov et al (2002).…”

Section: Astrophysical Examplesmentioning

confidence: 99%

Comparing Gas‐Phase and Grain‐catalyzed H₂Formation

Glover

2003

ApJ

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Because H 2 formation on dust-grain surfaces completely dominates gas-phase H 2 formation in local molecular clouds, it is often assumed that gas-phase formation is never important. In fact, it is the dominant mechanism in a number of cases. In this paper, I briefly summarize the chemistry of gas-phase H 2 formation and show that it dominates for dust-to-gas ratios less than a critical value D cr . I also show that D cr is simple to calculate for any given astrophysical situation and illustrate this with a number of examples, ranging from H 2 formation in warm atomic gas in the Milky Way to the formation of protogalaxies at high redshift.

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Metal abundances and ionization conditions in a possibly dust-free damped Lyα system at $\mathsf{\vec{z}=2.3}$

Cited by 73 publications

References 52 publications

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

A new comprehensive set of elemental abundances in DLAs

Comparing Gas‐Phase and Grain‐catalyzed H₂Formation

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Metal abundances and ionization conditions in a possibly dust-free damped Lyα system at $\mathsf{\vec{z}=2.3}$

Cited by 73 publications

References 52 publications

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

Relative abundance pattern along the profile of high redshift Damped Lyman-$\vec \alpha$ systems

A new comprehensive set of elemental abundances in DLAs

Comparing Gas‐Phase and Grain‐catalyzed H2Formation

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Product

Resources

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Comparing Gas‐Phase and Grain‐catalyzed H₂Formation