paper

The cosmological evolution of quasar black-hole masses

arXiv:astro-ph/0310267 · doi:10.1111/j.1365-2966.2004.08034.x

Abstract

Virial black-hole mass estimates are presented for 12698 quasars in the redshift interval 0.1<z<2.1, based on modelling of spectra from the Sloan Digital Sky Survey (SDSS) first data release. The black-hole masses of the SDSS quasars are found to lie between $\simeq10^{7}\Msun$ and an upper limit of $\simeq 3\times 10^{9}\Msun$, entirely consistent with the largest black-hole masses found to date in the local Universe. The estimated Eddington ratios of the broad-line quasars (FWHM\geq 2000 kms^{-1}) show a clear upper boundary at , suggesting that the Eddington luminosity is still a relevant physical limit to the accretion rate of luminous broad-line quasars at . By combining the black-hole mass distribution of the SDSS quasars with the 2dF quasar luminosity function, the number density of active black holes at is estimated as a function of mass. In addition, we independently estimate the local black-hole mass function for early-types using the and correlations. Based on the SDSS velocity dispersion function and the 2MASS band luminosity function, both estimates are found to be consistent at the high-mass end ($M_{bh}\geq 10^{8}\Msun$). By comparing the estimated number density of active black holes at with the local mass density of dormant black holes, we set lower limits on the quasar lifetimes and find that the majority of black holes with mass $\geq 10^{8.5}\Msun$ are in place by .

15 pages, 10 figures, revised version, accepted for publication by MNRAS

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