Breaking Degeneracies between Quasar Halo Occupation Distribution Models: Extending Direct Measurements of the Mean Occupation Distribution to Redshift 0.6
Abstract
Recent work on quasar clustering suggests a degeneracy in the halo occupation distribution (HOD) constrained from two-point correlation functions. To break this degeneracy, we made the first direct measurement of the mean occupation function (MOF) of quasars at redshift z ~ 0.2 from cross-matching SDSS DR7 quasars with clusters of galaxies drawn from the MaxBCG catalog. A limitation of our measurement is that at z ~ 0.2 the number of quasars declines rapidly compared to at higher redshift. To circumvent this limitation, we repeat our measurement using clusters drawn from the RedMapper catalog. The number of matched quasars increases significantly in this new analysis, as RedMapper clusters probe as high as z ~ 0.6. Preliminary results show that the MOF increases monotonically with halo mass. We also measure the variance, the second moment of the HOD, which closely resembles a Poisson distribution. The radial distribution of quasars within dark matter halos is well described by a power law with a slope of ~ -1. The conditional luminosity function (CLF) of quasars and conditional black hole mass function (CMF) show no dependence with host halo mass, similar to inferences drawn from measurements of the two-point correlation function.This work is supported by the National Science Foundation through grant number 1211112 and by NASA through ADAP award NNX12AE38G.
- Publication:
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American Astronomical Society Meeting Abstracts #224
- Pub Date:
- June 2014
- Bibcode:
- 2014AAS...22422105N