2003/03/15 by Mark Lacy, Lacy, Mark
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0303348
10 pages, in, "Carnegie Observatories Astrophysics Series, Vol. 1: Coevolution of Black Holes and Galaxies", ed. L. C. Ho (Pasadena: Carnegie Observatories, http://www.ociw.edu/ociw/symposia/series/symposium1/proceedings.html)
arxiv created 2003/03/15 · openalex publication_date 2003/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Black holes with masses MBH~108.5 MSun dominate the accretion history of the Universe. These black hole masses are typical of those found in radio-selected galaxies today, suggesting that the giant elliptical hosts of low redshift radio galaxies were the hosts of powerful, mostly radio-quiet, quasars in the high redshift Universe. The reason that all radio galaxies are found in such hosts may be the correlation of black hole mass with radio luminosity, but it is emphasized that accretion rate too plays an important role in the production of powerful radio jets. The tight K-z relation of luminous, high redshift, radio galaxies is probably a selection effect due to the selection on high black hole masses and high accretion rates. Luminous radio galaxies are the radio-loud part of the ``quasar-2'' population, and the ratio of radio-loud quasars to luminous radio galaxies, about 1:1, is so far our only good estimate of the relative numbers of quasar-1s and quasar-2s. The numbers of radio-quiet and radio-intermediate quasar-2s are still uncertain, but a much larger population than the quasar-1s would conflict with constraints from the present-day black hole mass density. A comparison of the number densities of dark matter haloes and the high redshift quasars, however, suggests that there are plenty of dark haloes capable of hosting the known high redshift AGN and thus room for a significant, but not huge, quasar-2 population.