Relation between accretion rate and jet power in early-type galaxies

UsingChandra X-rayand VLA radio observations for 20 early-type galaxies, we have confirmed the presence of a correlation between Bondiaccretion power andmechanical jet power in early-type galaxiespreviously reported by Allen et al. 2006.We show that a particularly strong correlation holds for galaxies withthermally unstableatmospheres, as indicated by the presence of coolgas traced by Hα+[NII] emission and min(tcool/tff)< ~10, whilefor the whole sample of galaxies the correlation is weaker.Importantly, we find a strong correlation between the mechanical jet powerand the mass of the central supermassive black holeand, although poorly constrained, a hint of an anti-correlation with the specific entropy (K) of the ambient gas inside the Bondi radius.The results indicate that at least for thermally unstable systems, the jet power is set primarily by the supermassive black hole mass. Since the central black hole mass of X-ray luminous early-type galaxies correlates with the total mass of the host halo, more massive systems undergoing thermally unstable cooling will naturally have larger jet powers.