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Astron. Astrophys. 333, 790-794 (1998)

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The correlations between the core dominance parameter and the core and extended powers of quasars

Yi-Ping Qin 1, Guang-Zhong Xie 1, Jin-Ming Bai 1, Jun-Hui Fan 2, Xue-Tang Zheng 3 and Shi-Min Wu 4

1 Yunnan Observatory, The Chinese Academy of Sciences, Kunming, Yunnan 650011, P.R. China
2 Center for Astrophysics, Guangzhou Normal University, Guangzhou, Guangdong 510400, P.R. China
3 Department of Physics, Nanjing University of Science and Technology, Nanjing, Jiangsu 210014, P.R. China
4 Department of Astronomy, Beijing Normal University, Beijing 100875, P.R. China

Received 4 December 1997 / Accepted 13 January 1998


We study the correlations between the core dominance parameter R and the core and extended powers [FORMULA] and [FORMULA] in the case of quasars with four different samples. In some samples, [FORMULA] is highly anti-correlated with logR while [FORMULA] is not at all correlated with logR. This effect seems to be common in the case of quasars when R is not very small. It obviously contradicts the conventional hypothesis of the core and extended emissions of radio sources in accordance with unified schemes and beaming models. Our study also implies that when R becomes larger, the anti-correlation between [FORMULA] and logR becomes more obvious while the correlation between [FORMULA] and logR becomes less obvious; when R becomes smaller, the above anti-correlation becomes less obvious while the correlation becomes more obvious. This effect can be interpreted by assuming that, for the lobe-dominated quasars, the emission of the core is beamed and oriented, while for core-dominated quasars, the emission of the core is unbeamed and isotropic.

Key words: quasars: general – radio continuum: galaxies

© European Southern Observatory (ESO) 1998

Online publication: April 28, 1998