Periodic Variations of the Jet Flow Lorentz Factor in 3C 273

作     者：SHAN－JieQian Xi－ZhenZhang 等 

作者机构：Max－Planck－InstitutfuerRadioastronomieAufdemHuegel69D－53121BonnGermany BeijingAstronomicalObservat 

出 版 物：《Chinese Journal of Astronomy and Astrophysics》 (中国天文和天体物理学报（英文版）)

年 卷 期：2001年第1卷第3期

页      面：236-244页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：from the Max-Planck-Institut fur Radioastronomie uring his visit the National Natural Science oundation of China(NSFC) 

主　　题：Galaxies: jets   quasars: individual: 3C273   Galaxies: nuclei   Radio Continuum: galaxies   Radiation mechanisms: nonthermal 

摘      要：C 273 has been observed with VLBI for more than 30 years. The entire data have shown that the position angle of the superluminal knots ejected from the core varies periodically with a period of ~15 years. Moreover, their apparent velocity observed during the period 1963 -- 1997 has systematically decreased by a factor of 2. These remarkable properties are explained in terms of a precessing jet model, in which the ejection Lorentz factor of the superluminal knots has been decreasing during the last thirty years and has superposed on it a short-term (~5 year) oscillation. The periodic variations derived by the model-fitting are compared with the variations in the optical flux density. Binary black hole models are briefly discussed to show possible relations of the observed periods to the periods involved in a binary system (orbital motion, spin of black hole, accretion-disk rotation and Newtonian-driven precession etc.).