High-resolution spectroscopy of flat-spectrum quasars

Free access article

This article has an erratum: [erratum]

Issue		A&A Volume 423, Number 3, September I 2004


Page(s)		943 - 954
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20035861

A&A 423, 943-954 (2004)
DOI: 10.1051/0004-6361:20035861

I. Redshifted emission and absorption in PKS 2145+067

A. Tappe and J. H. Black

Chalmers Centre for Astrophysics and Space Science, Onsala Space Observatory, Chalmers University of Technology, 43 992 Onsala, Sweden
e-mail: achim@oso.chalmers.se
e-mail: jblack@oso.chalmers.se

(Received 13 December 2003 / Accepted 24 May 2004 )

Abstract
We report Very Large Telescope (VLT) observations of the quasar PKS 2145+067 . We obtained high-resolution ( $R\approx100\,000$ or 3 $\rm\,km\,s^{-1}$ ) optical spectra with the UV-Visual Echelle Spectrograph (UVES) at the VLT UT2 telescope. The emission redshift measured from $\ion{[O}{iii]}$ is $z_{\rm em} =1.0003$ . In our spectra, the well-known intervening metal-rich absorption system at $z_{\rm abs} =0.79089$ shows $\ion{Mg}{ii}$ absorption lines resolved into 15 velocity components with a total spread of about 206 $\rm\,km\,s^{-1}$ . This absorption is consistent with a line of sight passing through the extended gaseous halo of a disk galaxy. The derived Doppler line broadening parameters are in the range b=2 to 5 $\rm\,km\,s^{-1}$ . We also detected absorption lines of $\ion{Mg}{i}$ , $\ion{Fe}{ii}$ , and $\ion{Ca}{ii}$ in the same system. The ionization state of the absorbing gas is analyzed and compared with previous studies of PKS 2145+067 . Finally, we discuss the implications of high-resolution data for proposed cosmological variations of the fine-structure constant.

Key words: galaxies: quasars: absorption lines -- galaxies: quasars: emission lines -- galaxies: quasars: individual: PKS 2145+067

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