Issue |
A&A
Volume 412, Number 2, December III 2003
|
|
---|---|---|
Page(s) | L29 - L32 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20031676 | |
Published online | 28 November 2003 |
Letter to the Editor
HI absorption in a gravitational lens at z ~ 0.7645
1
Kapteyn Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
2
RSAA, The Australian National University, Mount Stromlo Observatory, Cotter Road, ACT 2611, Australia
Corresponding authors: N. Kanekar, nissim@astro.rug.nl fbriggs@mso.anu.edu.au
Received:
7
October
2003
Accepted:
31
October
2003
We have used the Westerbork Synthesis Radio Telescope to
detect HI 21 cm absorption at in the gravitational lens system towards
PMN J0134-0931. The 21 cm profile has two broad components, with peak optical depths of
and
, at heliocentric redshifts
and
, respectively. The redshift of the
stronger component matches that of CaII H and K absorption detected earlier.
The absorption has a total velocity width of ~500 km s-1 (between nulls) and
an equivalent width of
km s-1. This would imply a total HI column density
of
cm-2, for a spin temperature of 200 K
and a covering factor of unity. The high estimated HI column density is
consistent with the presence of large amounts of dust at the lens redshift;
the intervening dust could be responsible for the extremely red colour
of the background quasar.
Key words: galaxies: individual: PMN J0134-0931 / gravitational lensing / radio lines / ISM
© ESO, 2003
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