Clustering analyses of 300,000 photometrically classified quasars. I. Luminosity and redshift evolution in quasar bias

Using similar to 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 similar to 50 h(-1) kpc to similar to 20 h(-1) Mpc from redshifts of (z) over bar similar to 0:75-2:28. We parameterize our clustering amplitudes using realistic dark matter models and find that a Lambda CDM power spectrum provides a superb fit to our data with a redshift-averaged quasar bias of b(Q)((z)) over bar (=1.40) = 2.41 +/- 0.08 (P-< x2 = 0.847) for sigma(8) 0:9. This represents a better fit than the best-fit power-law model [omega = (0.0493 +/- 0.0064)theta(-0.928 +/- 0.055); P-< x2 = 0.482]. We find b(Q) 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 to the star-galaxy separation in many photometric studies of galaxy clustering. We derive the mean mass of the dark matter halos hosting quasars as M-DMH (5.2 +/- 0.6); 10(12) h(-1) M (circle dot). At (z) over bar similar to 1.9 we find a 1.5 sigma deviation from luminosity-independent quasar clustering; this suggests that increasing our sample size by a factor of similar to 1.8 could begin to constrain any luminosity dependence in quasar bias at z similar to 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 greater than or similar to 50 h(-1) kpc. At z < 1.6, our analysis suggests that b(Q) is constant with luminosity to within Delta b(Q) similar to 0.6, and that, for g < 21, angular quasar autocorrelation measurements are unlikely to have sufficient statistical power at z less than or similar to 1.6 to detect any luminosity dependence in quasars' clustering.