Mass Functions of the Active Black Holes in Distant Quasars from the Sloan Digital Sky Survey Data Release 3

TL;DR

This paper derives the mass functions of actively accreting supermassive black holes in distant quasars from SDSS DR3 data, revealing their distribution over redshift and mass, and analyzing their evolution.

Contribution

It provides the first uniform, statistically significant black hole mass functions for SDSS DR3 quasars across a wide redshift range, extending previous luminosity function studies.

Findings

Mass functions show a rise and fall in active black hole density at all epochs.

High-mass decline slope is approximately -3.3 across epochs.

Sample incompleteness affects the observed low-mass end.

Abstract

We present the mass functions of actively accreting supermassive black holes over the redshift range 0.3 <= z <= 5 for a well-defined, homogeneous sample of 15,180 quasars from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3) within an effective area of 1644 square degrees. This sample is the most uniform statistically significant subset available for the DR3 quasar sample. It was used for the DR3 quasar luminosity function, presented by Richards et al., and is the only sample suitable for the determination of the SDSS quasar black hole mass function. The sample extends from i = 15 to i = 19.1 at z less than about 3 and to i = 20.2 for z greater than about 3. The mass functions display a rise and fall in the space density distribution of active black holes at all epochs. Within the uncertainties the high-mass decline is consistent with a constant slope of beta of about -3.3 at all epochs. This slope is similar to the bright end slope of the luminosity function for epochs below z = 4. Our tests suggest that the down-turn toward lower mass values is due to incompleteness of the quasar sample with respect to black hole mass. Further details and analysis of these mass functions will be presented in forthcoming papers.