A Statistical Analysis on the Morphology and Color of Galaxies Hosting Radio-loud Active Galactic Nuclei

Abstract

Abstract The properties of galaxies hosting radio-loud active galactic nuclei (AGN) have been investigated in order to find out the relation between morphology and color of galaxies and radio loudness. The concentration index is used to map the morphology of galaxies as early or late type. 4000 Å break strength and star-formation rate are used to quantify the state of galaxies as blue star forming or red quenched. Due to the environmental dependence of these properties, galaxies with the same environment have been considered. The results show that the prevalence of radio-loud AGN in early-type galaxies is independent of environment. This is confirmed by comparing a sample of galaxies hosting radio-loud AGN with a sample of galaxies hosting radio-quiet AGN or with a randomly selected galaxy sample from the total population of galaxies used in this study. In addition, it is shown that galaxies hosting radio-loud AGN are bluer indicating the role of cold gas in triggering AGN activity. Finally, the optically-selected radio-loud AGN show to have higher [O iii] luminosities compared with their radio-quiet counterparts. We argue the relation between radio size and luminosity with the [O iii] luminosity.