Spectral Indices of Core and Extended Components of Extragalactic Radio Sources
We use observed peak and total flux densities at 6cm and 20 cm to determine the spectral indices separately for the core and extended components of QSOs and galaxies, as well as their core-dominance parameters. Our results indicate that 1) Nine QSOs show both greater than 1.0 core-dominance parameters (those objects should be blazars) and greater than 0.5 spectral indices. The average core spectral index is αCore = 0.85±0.21 for the nine blazars, which implies that it is not reliable to use αradio = 0.0 for blazars. For the different subclasses, the core and extended spectral indices are as follows: for the blazars, αCore = 0.22±0.06 and αExt =0.77±0.12; the galaxies, αCore = 1.01±0.13 and αExt =0.83±0.21, and for the QSOs, αCore = 0.28±0.10 and αExt =0.68±0.08. 2) The core spectral index and core dominance parameter (R) show an anti-correlation, αC = (-1.28±0.26) log R+(0.65 ± 0.11); 3) R is approximately linearly correlated with redshift (z).
作 者： Jiang-Shui Zhang Jun-Hui Fan 作者单位： Center for Astrophysics, Guangzhou University, Guangzhou 510400 刊 名： 天体物理学报(英文版) ISTIC SCI 英文刊名： CHINESE JOURNAL OF ASTRONOMY AND ASTROPHYSICS 年，卷(期)： 2003 3(5) 分类号： P14 关键词： galaxies: active - radio continuum: galaxies