Issue |
A&A
Volume 450, Number 1, April IV 2006
|
|
---|---|---|
Page(s) | 53 - 57 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20054642 | |
Published online | 03 April 2006 |
The most metal-rich intervening quasar absorber known
1
European Southern Observatory, Garching-bei-München, Germany e-mail: cperoux@eso.org
2
Dept. of Physics and Astronomy, Univ. of South Carolina, Columbia, USA
3
Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, France
4
Dept. of Physics, Utkal University, Bhubaneswar, India
5
Dept. of Physics and Astronomy, Northwerstern University, Evanston, USA
6
Osservatorio di Trieste, Trieste, Italy
7
Dept. of Astronomy and Astrophysics, Univ. of Chicago, Chicago, USA
Received:
17
August
2005
Accepted:
3
January
2006
The metallicity in portions of high-redshift galaxies has
been successfully measured thanks to the gas observed in absorption in
the spectra of quasars, in the Damped Lyman-α systems
(DLAs). Surprisingly, the global mean metallicity derived from DLAs is
about 1/10th solar at leading to the so-called
“missing-metals problem”. In this paper, we present high-resolution
observations of a sub-DLA system at zabs = 0.716 with super-solar
metallicity toward SDSS J1323-0021. This is the highest metallicity
intervening high-H i quasar absorber currently known, and is only the second
super-solar such absorber known to date. We provide a detailed study of
this unique object from VLT/UVES spectroscopy. We derive
[Zn/H] = +0.61,
, [Cr/H] = < -0.53, [Mn/H] = -0.37, and
[Ti/H] = -0.61. Observations and photoionisation models using the
CLOUDY software confirm that the gas in this sub-DLA is predominantly
neutral and that the abundance pattern is probably significantly
different from a Solar pattern. Fe/Zn and Ti/Zn vary among the main
velocity components by factors of ∼3 and ∼35,
respectively, indicating non-uniform dust depletion. Mn/Fe is
super-solar in almost all components, and varies by a factor of
3 among the dominant components. It would be interesting to
observe more sub-DLA systems and determine whether they might
contribute significantly toward the cosmic budget of metals.
Key words: galaxies: abundances / intergalactic medium / quasars: absorption lines / quasars: individual: SDSS J1323-0021
© ESO, 2006
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