EDP Sciences
Free access
Volume 407, Number 3, September I 2003
Page(s) 899 - 904
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20030896

A&A 407, 899-904 (2003)
DOI: 10.1051/0004-6361:20030896

The core dominance parameter of extragalactic radio sources

J. H. Fan and J. S. Zhang

Center for Astrophysics, Guangzhou University, Guangzhou 510400, PR China
    e-mail: fjh@gzhu.edu.cn
(Received 20 January 2003 / Accepted 12 June 2003 )

In this paper, based on a paper by Liu and Zhang (2002), we have chosen a sample of 542 extragalactic sources (27 BL Lac objects, 300 galaxies (radio galaxies and Seyfert galaxies), and 215 quasars), for which we have calculated the core-dominance parameters and investigated the relation between core-dominance parameter and the core and extended luminosities. The core-dominance parameter of galaxies is smaller than that in quasars, which is smaller than that in BL Lac objects. log $R = -1.40 \pm0.74$ for galaxies, log $R = -0.53 \pm0.92$ for quasars, and log $R = 0.01 \pm0.65$ for BL Lac objects on average respectively. For quasars, there is clear correlation between the core-luminosity and core-dominance parameter and an anti-correlation between the extended luminosity and the core-dominance parameter, which is explained by the beaming effect.

Key words: BL Lacertae objects: general -- quasars: general -- galaxies: Seyfert -- galaxies: jets

Offprint request: Dr. J. H. Fan, fjh@gzhu.edu.cn

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