The Independence of AGN Black Hole Mass and Radio-Loudness

Abstract

We revisit the issue of whether radio loudness in AGN is associated with central black hole mass, as has been suggested in the literature. We present new estimates of black hole mass for 295 AGN (mostly radio-quiet), calculating their radio loudnesses from published radio and optical fluxes, and combine with our previously published values, for a sample of 452 AGN for which both black hole mass and radio loudness (or upper limits thereto) are known. Among the radio-quiet AGN, there are now many black holes with mass larger than $10^{9}$ $M_{\odot}$, extending to the same high black hole masses as radio-loud AGN of the same redshifts. Over the full sample, the black hole masses of radio-loud and radio-quiet AGN span the same large range, $10^6 - 10^{10} M_\odot$. We conclude that radio loudness in AGN does not depend strongly on central black hole mass.