Optical and radio properties of extragalactic radio sources with recurrent jet activity

Abstract

We present a sample of 74 radio sources with recurrent jet activity. The\nsample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected\nfrom the published data or are newly recognized. The sample's redshift range is\n0.002 < z < 0.7 and the size of inner and outer structures varies from 0.02 to\n4248 kpc. We analyse the optical and radio properties of the sample and compare\nthem with the characteristics of ordinary one-off FRII radio sources. With the\nhelp of stellar population modelling, we derive black hole masses and stellar\nmasses of host galaxies of 35 restarting radio sources, finding that the black\nhole masses in restarting radio sources are comparable to those of typical\nsingle-cycle FRII radio sources. The obtained median values of log M$_{BH}$ are\n8.58 and 8.62 M$_{\\odot}$ Unlike the black hole masses, the stellar masses in\nrestarting radio sources tend to be smaller than in the FRII sources. Although\nthe stellar populations of the hosts of recurrent activity sources are\ndominated by old stars, a significant fraction of young stars can be observed\nas well. Based on the Sloan Digital Sky Survey photometric observations, we\nalso analyse the morphology of the host galaxies and obtained significantly\nsmaller concentration indices for the restarting radio sources when compared to\nthe classical FRII hosts. This effect can be interpreted as a result of\nfrequent merger events in the history of host galaxies of restarting radio\nsources.\n