2002A&A...385..802L


Query : 2002A&A...385..802L

2002A&A...385..802L - Astronomy and Astrophysics, volume 385, 802-815 (2002/4-3)

Dust depletion and abundance pattern in damped Lyα systems: A sample of Mn and Ti abundances at z < 2.2.

LEDOUX C., BERGERON J. and PETITJEAN P.

Abstract (from CDS):

We analyse a sample of 24 damped Lyman-α (DLA)/moderate DLA systems at intermediate redshifts, 0.3<zabs<2.2, all with measurement of the weak Mnii absorption lines, to investigate which elemental ratios could possibly be used as tracers of either dust depletion or nucleosynthesis effects. We applied a component-by-component analysis to the five systems of the sample with new observations and, using this procedure, re-analyzed data gathered from the literature whenever possible. We show that the standard method which uses column densities integrated over the whole absorption profiles could substantially underestimate the abundance of rare elements relative to Fe. We find a correlation between the observed [Si/Fe] and [Zn/Fe] ratios, present in our sample at the 2.9σ significance level. This correlation is fully consistent with a dust depletion sequence only for a Galactic warm disk cloud or halo cloud depletion pattern. The correlation between [Mn/Fe] and [Zn/Fe], detected at the 3.2σ significance level, cannot be accounted for by any dust depletion sequence: it implies either variations of the intrinsic Mn abundance relative to Fe from -0.3 to +0.1dex and/or a relation between depletion level and metallicity. The correlation between [Mn/Fe] and metallicity (2.6σ significance level) strengthens the assumption of intrinsic variations of [Mn/Fe] although some marginal correlation between [Zn or Si/Fe] and [Zn/H] is present as well. Extension of the sample toward low metallicity is needed to confirm the correlation between depletion level and metallicity. The variations of [Ti/Fe] vs. [Zn/Fe] cannot be fitted by a single dust depletion sequence either. We then adopt a warm disk cloud or halo cloud depletion pattern and compare the resulting dust-corrected abundance ratios to those observed in Galactic and SMC stars. At high metallicity, [Fe/H]dc>-0.5, the intrinsic abundance pattern of Si, Ti, Cr and Mn in DLA absorbers closely follows the trends observed in Galactic stars and these absorbers should thus have a chemical evolution similar to that of our Galaxy. At lower metallicity, some absorbers do follow the trends present in Galactic stars but a substantial fraction of them have elemental ratios (in particular [Si/Fe]dc and [Mn/Fe]dc) closer to the solar values than Galactic stars. This could be explained by a larger contribution of type Ia supernovae to the chemical enrichment of these DLA absorbers than in Galactic stars of similar metallicity. This metal-poor DLA absorber population could trace HI-rich dwarf galaxies.

Abstract Copyright:

Journal keyword(s): cosmology: observations - galaxies: halos - galaxies: ISM - quasars: absorption lines

Simbad objects: 24

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Number of rows : 24
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 LBQS 0058+0155 QSO 01 00 54.1201107072 +02 11 36.331220364   17.48 17.16     ~ 161 0
2 QSO B0118-272 BLL 01 20 31.6628068344 -27 01 24.636341064   15.89 15.56 15.49   ~ 256 1
3 QSO J0217+0144 QSO 02 17 48.95475095 +01 44 49.6990271   16.74 16.09 18.51 13.29 ~ 403 1
4 QSO B0216+0803 QSO 02 18 57.3582544488 +08 17 27.346030260     18.1     ~ 90 0
5 QSO J0304-2211 QSO 03 04 49.8652311288 -22 11 51.882127548   16.43 16.40     ~ 108 0
6 QSO B0449-135 QSO 04 51 42.7191531552 -13 20 46.950207288   18.9 17.0     ~ 54 2
7 QSO B0450-1310 QSO 04 53 13.5744238944 -13 05 55.085318988   13.2 16.5     ~ 89 2
8 QSO J0455-4216 QSO 04 55 23.0626782912 -42 16 17.398553052   17.77 17.06     ~ 138 0
9 QSO B0454+0356 QSO 04 56 47.1747907776 +04 00 52.946102484   16.76 16.53 16.26   ~ 235 1
10 QSO B0528-2505 QSO 05 30 07.9627395840 -25 03 29.900044512   18.17 17.34 17.7   ~ 412 0
11 QSO B0551-36 QSO 05 52 46.1824785360 -36 37 27.608212524   17.72 17.57     ~ 93 0
12 QSO J0938+4128 QSO 09 38 57.0175740480 +41 28 21.216772452   16.94 16.75     ~ 137 1
13 QSO B1104-181 QSO 11 06 33.3845199936 -18 21 23.829049296   15.8 15.9 15.7   ~ 318 1
14 QSO B1122-168 QSO 11 24 42.8658917592 -17 05 17.389038732   16.5 16.5 16.1   ~ 126 1
15 4C -02.55 QSO 12 32 00.0159535440 -02 24 04.793069304   17.41 17.06 16.4   ~ 410 1
16 LB 19 QSO 12 50 05.7146863848 +26 31 07.598352000   16.12 15.92     ~ 200 0
17 3C 286 Sy1 13 31 08.2883506368 +30 30 32.960091564   17.51 17.25     ~ 4172 2
18 7C 1351+3153 QSO 13 54 05.3922907896 +31 39 02.432250180   19.03 18.71     ~ 64 1
19 7C 1354+2552 QSO 13 57 06.5354509152 +25 37 24.494694024   19.13 18.93     ~ 96 1
20 4C 23.43 Sy1 16 24 39.0838297968 +23 45 12.223370412   17.91 17.47     ~ 329 1
21 QSO B1946+770 QSO 19 44 54.8532392016 +77 05 52.673448048     15.8     ~ 151 0
22 QSO B2128-123 BLL 21 31 35.2617909696 -12 07 04.795364172   16.33 16.11 15.87   ~ 442 1
23 LBQS 2206-1958A QSO 22 08 52.0729138920 -19 43 59.866776948   17.49 17.33     ~ 213 0
24 QSO B2206-1959 QSO 22 09 00.6950774976 -19 44 19.743416484     18.65     ~ 83 0

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2023.02.02-19:44:27

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