Black hole spin properties of 130 AGN

Abstract

Supermassive black holes may be described by their mass and spin. When supermassive black holes are active, the activity provides a probe of the state of the black hole system. The spin of a hole can be estimated when the black hole mass and beam power of the source are known for sources with powerful outflows. Seventy-five sources for which both the black hole mass and beam power could be obtained are identified and used to obtain estimates of black hole spins. The 75 supermassive black holes studied include 52 FRII radio galaxies and 23 FRII radio loud quasars with redshifts ranging from about zero to two. The new values are combined with those obtained previously for 19 FRII radio galaxies, 7 FRII radio loud quasars, and 29 radio sources associated with CD galaxies to form samples of 71 FRII radio galaxies, 30 FRII quasars, and a total sample of 130 spin values; all of the sources are associated with massive elliptical galaxies. The new values obtained are similar to those obtained earlier at similar redshift, and range from about 0.1 to 1 for FRII sources. The overall results are consistent with those obtained previously: the spins tend to decrease with decreasing redshift for the FRII sources studied. There is a hint that the range of values of black hole spin at a given redshift is larger for FRII quasars than for FRII radio galaxies. There is no indication of a strong correlation between supermassive black hole mass and spin for the supermassive black holes studied here. The relation between beam power and black hole mass is obtained and used as a diagnostic of the outflows and the dependence of the magnetic field strength on black hole mass.