High-resolution spectroscopy of flat-spectrum quasars ^*

I. Redshifted emission and absorption in PKS 2145+067

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 ( or 3) optical spectra with the UV-Visual Echelle Spectrograph (UVES) at the VLT UT2 telescope. The emission redshift measured from  is . In our spectra, the well-known intervening metal-rich absorption system at shows absorption lines resolved into 15 velocity components with a total spread of about 206. 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 to 5. We also detected absorption lines of , , and  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.