We measure the clustering of a sample of photometrically selected luminous red galaxies around a low redshift ( 0.2 < z < 0.6 ) sample of quasars selected from the Sloan Digital Sky Survey Data Release 5 .
We make use of a new statistical estimator to obtain precise measurements of the LRG auto-correlations and constrain halo occupation distributions for them .
These are used to generate mock catalogs which aid in interpreting our quasar-LRG cross correlation measurements .
The cross correlation is well described by a power law with slope 1.8 \pm 0.1 and r _ { 0 } = 6 \pm 0.5 h ^ { -1 } Mpc , consistent with observed galaxy correlation functions .
We find no evidence for ‘ excess ’ clustering on 0.1 Mpc scales and demonstrate that this is consistent with the results of Serber et al .
( 59 ) and Strand , Brunner & Myers ( 67 ) , when one accounts for several subtleties in the interpretation of their measurements .
Combining the quasar-LRG cross correlation with the LRG auto-correlations , we determine a large-scale quasar bias b _ { QSO } = 1.09 \pm 0.15 at a median redshift of 0.43 , with no observed redshift or luminosity evolution .
This corresponds to a mean halo mass \langle M \rangle \sim 10 ^ { 12 } h ^ { -1 } M _ { \odot } , Eddington ratios from 0.01 to 1 and lifetimes less than 10 ^ { 7 } yr .
Using simple models of halo occupation , these correspond to a number density of quasar hosts greater than 10 ^ { -3 } h ^ { 3 } { Mpc } ^ { -3 } and stellar masses less than 10 ^ { 11 } h ^ { -1 } M _ { \odot } .
The small-scale clustering signal can be interpreted with the aid of our mock LRG catalogs , and depends on the manner in which quasars inhabit halos .
We find that our small scale measurements are inconsistent with quasar positions being randomly subsampled from halo centers above a mass threshold , requiring a satellite fraction > 25 per cent .