We present a direct measurement of the mean halo occupation distribution ( HOD ) of galaxies taken from the eleventh data release ( DR11 ) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey ( BOSS ) .
The HOD of BOSS low-redshift ( LOWZ : 0.2 < z < 0.4 ) and Constant-Mass ( CMASS : 0.43 < z < 0.7 ) galaxies is inferred via their association with the dark-matter halos of 174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey ( XCS ) .
Halo masses are determined for each galaxy cluster based on X-ray temperature measurements , and range between { log _ { 10 } } ( M _ { 180 } / M _ { \odot } ) = 13 - 15 .
Our directly measured HODs are consistent with the HOD-model fits inferred via the galaxy-clustering analyses of Parejko et al .
for the BOSS LOWZ sample and White et al .
for the BOSS CMASS sample .
Under the simplifying assumption that the other parameters that describe the HOD hold the values measured by these authors , we have determined a best-fit alpha-index of 0.91 \pm 0.08 and 1.27 ^ { +0.03 } _ { -0.04 } for the CMASS and LOWZ HOD , respectively .
These alpha-index values are consistent with those measured by White et al .
and Parejko et al .
In summary , our study provides independent support for the HOD models assumed during the development of the BOSS mock-galaxy catalogues that have subsequently been used to derive BOSS cosmological constraints .