Quasar Remnants: Dark and Well-Fed.

Present-epoch giant elliptical galaxies, apparently the dormant remnants of previously active quasars, now harbor Super-Massive Black Hole nuclei built-up via early galactic mergers followed by the steadier growth associated with accretion of matter from the galactic bulge. We focus here on the growth from accretion. In order for these nuclei to serve as viable compact dynamos for generating ultra-relativistic cosmic rays, it is necessary for them to have a substantial accretion-supported magnetic field, an especially dark radiation environment, and near-maximal spin. In addition to using the luminosity of the galactic bulge to estimate its mass and exploiting the velocity dispersion of stars in the bulge to infer the core black hole mass, we are now employing B - V colors to determine the galaxy “Heuristic Merger Age”—the time since its last major galactic merger. It is known that the most massive black holes are found in giant elliptical galaxies. Based on a large sample of nearby giant ellipticals located at z < 0.02 (with a median age of 6.6 Gyr), we find a statistically significant systematic increase of black hole to bulge mass ration with age. Those galaxies that have merged farther in the past have a larger present black hole mass than those that have merged more recently. The bulge mass itself is essentially age invariant. We find that the inferred growth since the last major galactic merger corresponds to a suitably high rate of accretion that can readily account for at least 90% the present mass evident for most of the largest black holes in our sample. If the final growth stage (e.g., for mass doubling) involves disk accretion, the associated mass transfer is then sufficient to assure a spun-up canonical Kerr hole. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]