Issue |
A&A
Volume 454, Number 1, July IV 2006
|
|
---|---|---|
Page(s) | 151 - 164 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20054742 | |
Published online | 03 July 2006 |
Extinction and metal column density
of HI regions up to redshift z
1
Osservatorio Astronomico di Trieste, Istituto Nazionale di Astrofisica, Trieste, Italy e-mail: vladilo@ts.astro.it
2
Department of Theoretical Astrophysics, Ioffe Physico-Technical Institute, St. Petersburg, Russia
3
European Southern Observatory, Garching-bei-München, Germany
4
Department of Physics, Utkal University, Bhubaneswar, India
5
Department of Physics and Astronomy, University of South Carolina, Columbia, USA
6
Department of Astronomy and Astrophysics, University of Chicago, Chicago, USA
7
Enrico Fermi Institute, University of Chicago, Chicago, USA
Received:
21
December
2005
Accepted:
10
April
2006
We used the photometric database of the Sloan Digital Sky Survey (SDSS)
to estimate the reddening of 13 SDSS quasars selected on the basis
of the presence of zinc absorption lines in an intervening Damped Ly α (DLA) system.
In 5 of these quasars the reddening is detected at 2σ confidence level
in two independent color indices of the SDSS ugriz photometric system. A detailed analysis of the data supports an origin of the reddening in the intervening absorbers.
We used these rare measurements of extinction in DLA systems
to probe the relation between extinction and metal column density
in the interval of absorption redshift
.
We find that the mean extinction in the V band per atom of iron
in the dust is remarkably similar to that found in interstellar clouds of
the Milky Way. This result lends support to
previous estimates of the dust obscuration effect in DLA systems
based on a Milky Way extinction/metal column density relation.
We propose a simple mechanism, based on dust grain destruction/accretion properties,
which may explain the approximate constancy of the extinction per atom of iron
in the dust.
Key words: ISM: dust, extinction / galaxies: abundances / galaxies: ISM / galaxies: high-redshift / galaxies: quasars: absorption lines
© ESO, 2006
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