On the prevalence of radio-loud AGN in brightest cluster galaxies: implications for AGN heating of cooling flows

(Abridged) The prevalence of radio-loud AGN activity in present-day massive halos is determined using a sample of 625 nearby groups and clusters selected from the Sloan Digital Sky Survey. Brightest group and cluster galaxies (BCGs) are more likely to host a radio-loud AGN than other galaxies of the same stellar mass (by less than a factor of two at a stellar mass of 5e11 M_sun, but over an order of magnitude below 1e11 M_sun). The distribution of radio luminosities for BCGs does not depend on mass, however, and is similar to that of field galaxies of the same stellar mass. Neither the radio-loud fraction nor the radio luminosity distribution of BCGs depends strongly on the velocity dispersion of the host cluster. The radio-AGN fraction is also studied as a function of distance from the cluster center. Only within 0.2 r_200 do cluster galaxies exhibit an enhanced likelihood of radio-loud AGN activity, which approaches that of the BCGs. The radio-loud AGN properties of both BCGs and non-BCGs can naturally be explained if this activity is fuelled by cooling from hot gas surrounding the galaxy. Using observational estimates of the mechanical output of the radio jets, the time-averaged energy output associated with recurrent radio source activity is estimated for all group/cluster galaxies. Within the cooling radius of the cluster, the radio-mode heating associated with the BCG dominates over that of all other galaxies combined. The scaling between total radio-AGN energy output and cluster velocity dispersion is considerably shallower than the sigma^4 scaling of the radiative cooling rate. Thus, unless the efficiency of converting AGN mechanical energy into heating increases by 2-3 orders of magnitude between groups and rich clusters, radio-mode heating will not balance radiative cooling in systems of all masses