EDP Sciences
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A&A
Volume 492, Number 3, December IV 2008
Page(s) 725 - 730
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:200810041


A&A 492, 725-730 (2008)
DOI: 10.1051/0004-6361:200810041

Submillimeter water and ammonia absorption by the peculiar z $\approx$ 0.89 interstellar medium in the gravitational lens of the PKS 1830-211 system

K. M. Menten1, R. Güsten1, S. Leurini2, S. Thorwirth1, C. Henkel1, B. Klein1, C. L. Carilli3, and M. J. Reid4

1  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
    e-mail: [kmenten;rguesten;sthorwirth;chenkel;bklein]@mpifr-bonn.mpg.de
2  ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
    e-mail: sleurini@eso.org
3  National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801-0387, USA
    e-mail: ccarilli@nrao.edu
4  Harvard-Smithsonian Center for Astrophysics 60 Garden Street Cambridge, MA 02138, USA
    e-mail: reid@cfa.harvard.edu

Received 24 April 2008 / Accepted 15 October 2008

Abstract
Using the Atacama Pathfinder Experiment (APEX) telescope, we have detected the rotational ground-state transitions of ortho-ammonia and ortho-water toward the redshift $\approx$0.89 absorbing galaxy in the PKS 1830-211 gravitational lens system. We discuss our observations in the context of recent space-borne data obtained for these lines with the SWAS and Odin satellites toward Galactic sources. We find commonalities, but also significant differences between the interstellar media in a galaxy at intermediate redshift and in the Milky Way. Future high-quality observations of the ground-state ammonia transition in PKS 1830-211, together with inversion line data, will lead to strong constraints on the variation in the proton to electron mass ratio over the past 7.2 Gyr.


Key words: cosmology: observations -- gravitational lensing -- astrochemistry -- ISM: abundances -- ISM: molecules



© ESO 2008