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The HST Sample of Radio-Loud Quasars: Emission Lines from Lyα to Hβ

Published online by Cambridge University Press:  12 April 2016

Beverley J. Wills ,
M.S. Brotherton ,
D. Wills ,
K.L. Thompson ,
J. A. Baldwin ,
R. F. Carswell ,
I.W.A. Browne ,
H. Netzer  and
P.J. Francis
Beverley J. Wills
Affiliation:
McDonald Observatory and Department of Astronomy, RLM 15.308, University of Texas at Austin, TX 78712, USA
M.S. Brotherton
Affiliation:
McDonald Observatory and Department of Astronomy, RLM 15.308, University of Texas at Austin, TX 78712, USA
D. Wills
Affiliation:
McDonald Observatory and Department of Astronomy, RLM 15.308, University of Texas at Austin, TX 78712, USA
K.L. Thompson
Affiliation:
McDonald Observatory and Department of Astronomy, RLM 15.308, University of Texas at Austin, TX 78712, USA
J. A. Baldwin
Affiliation:
CTIO, Casilla 603, La Serena, Chile
R. F. Carswell
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge, CB3 OH A, UK
I.W.A. Browne
Affiliation:
Nuffield Radio Astronomy Laboratories, Jodrell Bank, Cheshire SK11 9DL, UK
H. Netzer
Affiliation:
Tel-Aviv University, Tel-Aviv, Israel
P.J. Francis
Affiliation:
School of Physics, University of Melbourne, Parkville, Victoria 3052, Australia

Extract

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We have obtained HST and ground-based spectrophotometry of a sample of ~61 radio-loud quasars from shortward of Lyα to longward of Hβ. The aim was to investigate the dependence of quasar properties on orientation of the central engine axis to the observer’s line of sight. As an approximate measure of inclination we use the radio core-dominance, i.e., the ratio of beamed radiocore emission to the emission in the extended lobes at 5 GHz rest frequency. About half the radio sources have core-dominance greater than unity (jet or axis pointed close to our line of sight). Quasar pairs were matched in radio lobe luminosity and redshift to reduce bias caused by strong dependences on intrinsic luminosity.

Observation and reduction techniques were standard, and the spectral resolution is equivalent to 230–400 km s−1 (Wills et al. 1993). We have performed correlation analyses among emission-line and continuum parameters, as well as spectral principal-component analyses (SPCA, Francis et al. 1992).

Type
II. Broad Emission Lines
Information
International Astronomical Union Colloquium , Volume 159: Emission Lines in Active Galaxies: New Methods and Techniques , 1997 , pp. 104 - 105
Copyright
Copyright © Astronomical Society of the Pacific 1997

References

Francis, P.J., et al. 1992, ApJ, 398, 476.CrossRefGoogle Scholar
Wills, B.J., et al. 1993, ApJ, 410, 534.Google Scholar
Wills, D., et al. 1997, this volume.Google Scholar