Clustering Analyses of 300,000 Photometrically Classified Quasars–i. Luminosity and Redshift Evolution in Quasar Bias

Using∼300,000 photometrically classified quasars, by far the largest quasar sample ever used for such analyses, we study the redshift and luminosity evolution of quasar clustering on scales of ∼50 h kpc to ∼20 h Mpc from redshifts of z̄ ∼0.75 to z̄ ∼2.28. We parameterize our clustering amplitudes using realistic dark matter models, and find that a ΛCDM power spectrum provides a superb fit to our data with a redshift-averaged quasar bias of b Q = 2.41± 0.08 (P<χ2 = 0.847) for σ8 = 0.9. This represents a better fit than the best-fit power-law model (ω = 0.0493± 0.0064θ; P<χ2 = 0.482). We find bQ increases with redshift. This evolution is significant at > 99.6% using our data set alone, increasing to > 99.9999% if stellar contamination is not explicitly parameterized. We measure the quasar classification efficiency across our full sample as a = 95.6±4.4 1.9%, a star-quasar separation comparable with the star-galaxy separation in many photometric studies of galaxy clustering. We derive the mean mass of the dark matter halos hosting quasars as MDMH = 5.2± 0.6× 10 hM⊙. At z̄ ∼ 1.9 we find a 1.5σ deviation from luminosity-independent quasar clustering; this suggests that increasing our sample size by a factor of ∼1.8 could begin to constrain any luminosity dependence in quasar bias at z ∼ 2. Our results agree with recent studies of quasar environments at z < 0.4, which detected little luminosity dependence to quasar clustering on proper scales ∼> 50 h kpc. At z < 1.6, our analysis suggests that bQ is constant with luminosity to within ∆bQ ∼ 0.6, and that, for g < 21, angular quasar autocorrelation measurements are unlikely to have sufficient statistical power at z ∼< 1.6 to detect any luminosity dependence in quasars’ clustering. Subject headings: cosmology: observations — large-scale structure of universe — quasars: general — surveys