EDP Sciences
Free Access
Issue
A&A
Volume 399, Number 2, February IV 2003
Page(s) 469 - 487
Section Galactic structure and dynamics
DOI https://doi.org/10.1051/0004-6361:20021803
Published online 07 February 2003


A&A 399, 469-487 (2003)
DOI: 10.1051/0004-6361:20021803

The Parkes quarter-Jansky flat-spectrum sample

2. New optical spectra and redshift measurements
I. M. Hook1, P. A. Shaver2, C. A. Jackson3, J. V. Wall1 and K. I. Kellermann4

1  Department of Physics, University of Oxford, Nuclear & Astrophysics Laboratory, Keble Road, Oxford, OX1 3RH, UK
2  European Southern Observatory, Karl Schwarzschild Straße 2, 85748 Garching b. München, Germany
3  Research School of Astronomy & Astrophysics, The Australian National University, Mount Stromlo Observatory, Canberra, Australia
4  National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA (The National Radio Astronomy Observatory is operated by Associated Universities Inc. under a cooperative agreement with the National Science Foundation.)

(Received 16 May 2002 / Accepted 29 November 2002 )

Abstract
We present optical spectra and redshift measurements for 178 flat-spectrum objects from the Parkes quarter-Jansky flat-spectrum sample. These spectra were obtained in order to compile a complete sample of quasars for use in a study of quasar evolution. We present a composite optical spectrum made from the subset of 109 quasars that have flux densities in the range $0.25~{\rm Jy} < S_{\rm 2.7~GHz}< 0.5~{\rm Jy}$, and make a comparison with a composite for radio-quiet QSOs from the Large Bright Quasar Survey. Our large sample of radio-loud quasars allows us to strengthen previous reports that the Ly $\alpha$ and CIV emission lines have larger equivalent width in radio-loud quasars than radio-quiet QSOs to greater than the 3 $\sigma$ level. However we see no significant difference in the equivalent widths of CIII] or MgII. We also show that the flux decrements across the Lyman- $\alpha$ line ( $D_{\rm A}$) measured from these spectra show the same trend with redshift as for optically selected QSOs.


Key words: quasars: general

Offprint request: I. M. Hook, imh@astro.ox.ac.uk

SIMBAD Objects
Tables at the CDS



© ESO 2003

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.