Clustering of obscured and unobscured quasars in the Bootes field:
  Placing rapidly growing black holes in the cosmic web
  We present the first measurement of the spatial clustering of mid-infrared
selected obscured and unobscured quasars, using a sample in the redshift range
0.7 < z < 1.8 selected from the 9 deg^2 Bootes multiwavelength survey. Recently
the Spitzer Space Telescope and X-ray observations have revealed large
populations of obscured quasars that have been inferred from models of the
X-ray background and supermassive black hole evolution. To date, little is
known about obscured quasar clustering, which allows us to measure the masses
of their host dark matter halos and explore their role in the cosmic evolution
of black holes and galaxies. In this study we use a sample of 806 mid-infrared
selected quasars and ~250,000 galaxies to calculate the projected quasar-galaxy
cross-correlation function w_p(R). The observed clustering yields
characteristic dark matter halo masses of log (M_halo [h^-1 M_sun]) =
12.7^+0.4_-0.6 and 13.3^+0.3_-0.4 for unobscured quasars (QSO-1s) and obscured
quasars (Obs-QSOs), respectively. The results for QSO-1s are in excellent
agreement with previous measurements for optically-selected quasars, while we
conclude that the Obs-QSOs are at least as strongly clustered as the QSO-1s. We
test for the effects of photometric redshift errors on the optically-faint
Obs-QSOs, and find that our method yields a robust lower limit on the
clustering; photo-z errors may cause us to underestimate the clustering
amplitude of the Obs-QSOs by at most ~20%. We compare our results to previous
studies, and speculate on physical implications of stronger clustering for
obscured quasars.
