Spectral Indices of Core and Extended Components of Extragalactic Radio Sources

Abstract

We use observed peak and total flux densities at 6cm and 20cm 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 Core = 0.85±0.21 for the nine blazars, which implies that it is not reliable to use radio = 0.0 for blazars. For the dierent subclasses, the core and extended spectral indices are as follows: for the blazars, Core = 0.22±0.06 and Ext =0.77±0.12; the galaxies, Core = 1.01±0.13 and Ext =0.83±0.21, and for