The Sloan Digital Sky Survey Quasar Survey: Quasar Luminosity Function from Data Release 3

Abstract

We determine the number counts and z = 0-5 luminosity function for a well-defined, homogeneous sample of quasars from the Sloan Digital Sky Survey (SDSS). We conservatively define the most uniform statistical sample possible, consisting of 15,343 quasars within an effective area of 1622 deg 2 that was derived from a parent sample of 46,420 spectroscopically confirmed broad-line quasars in the 5282 deg 2 of imaging data from SDSS Data Release Three. The sample extends from i = 15 to i = 19.1 at z 3 and to i = 20.2 for z 3. The number counts and luminosity function agree well with the results of the Two-Degree Field QSO Redshift Survey (2QZ) at redshifts and luminosities where the SDSS and 2QZ quasar samples overlap, but the SDSS data probe to much higher redshifts than does the 2QZ sample. The number density of luminous quasars peaks between redshifts 2 and 3, although uncertainties in the selection function in this range do not allow us to determine the peak redshift more precisely. Our best fit model has a flatter bright end slope at high redshift than at low redshift. For z < 2.4 the data are best fit by a redshift-independent slope of β = −3.1 (Φ(L) ∝ L β ). Above z = 2.4 the slope flattens with redshift to β −2.37 at z = 5. This slope change, which is significant at the 5-sigma level, must be accounted for in models of the evolution of accretion onto supermassive black holes.

Constraints on cosmic hemispherical power anomalies from quasars

“…13 of Ref. [62]). Even the 1% dipole obtained from the first fit would lead to a calibration-induced dipole of 1.8% in the density of quasars, which is much less than our 5-10% statistical errors.…”

Observational evidence that positive and negative AGN feedback depends on galaxy mass and jet power

“…Richards et al 2006), L bol = 8.5λL12µm. The bolometric luminosity for the quasar sample has been computed from the 3000Å luminosity (L3000) using the SDSS spectral fits and a bolometric correction of 5.15 from the composite SED in Richards et al (2006), L bol = 5.15λL3000 . Fernandes et al (2011) have computed the bolometric luminosity for the quasar sample based on the rest-frame 12µm luminosity, following the same method as the one applied for the radio galaxies.…”

“…For the radio galaxy sample, we adopted the values of L bol calculated by Fernandes et al (2015) from the rest-frame 12µm luminosity, using a bolometric correction of 8.5 (e.g. Richards et al 2006), L bol = 8.5λL12µm. The bolometric luminosity for the quasar sample has been computed from the 3000Å luminosity (L3000) using the SDSS spectral fits and a bolometric correction of 5.15 from the composite SED in Richards et al (2006), L bol = 5.15λL3000 .…”

Cold dust emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: dependence on luminosity, obscuration and AGN activity

“…The galaxy templates constitute a set of Bruzual & Charlot (2003) stellar population synthesis models with a Chabrier (2003) initial mass function and assuming exponentially declining star formation histories with varying amounts of dust reddening. The AGN template is the mean quasar SED from Richards et al (2006), again with varying amounts of reddening. This choice of AGN template is appropriate for the luminous XMM-COSMOS AGN investigated in this work.…”