Cross-correlation of SDSS DR7 quasars and DR10 BOSS galaxies: The weak luminosity dependence of quasar clustering at z ∼ 0.5
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States)
- Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720 (United States)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)
- Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States)
- Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520 (United States)
- Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
- Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)
- Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States)
We present the measurement of the two-point cross-correlation function (CCF) of 8198 Sloan Digital Sky Survey Data Release 7 quasars and 349,608 Data Release 10 CMASS galaxies from the Baryonic Oscillation Spectroscopic Survey at 0.3 < z < 0.9. The CCF can be reasonably well fit by a power-law model ξ{sub QG}(r) = (r/r {sub 0}){sup –γ} on projected scales of r{sub p} = 2-25 h {sup –1} Mpc with r {sub 0} = 6.61 ± 0.25 h {sup –1} Mpc and γ = 1.69 ± 0.07. We estimate a quasar linear bias of b{sub Q} = 1.38 ± 0.10 at (z) = 0.53 from the CCF measurements, which corresponds to a characteristic host halo mass of ∼4 × 10{sup 12} h {sup –1} M {sub ☉}, compared with a ∼10{sup 13} h {sup –1} M {sub ☉} characteristic host halo mass for CMASS galaxies. Based on the clustering measurements, most quasars at z-bar ∼0.5 are not the descendants of their higher luminosity counterparts at higher redshift, which would have evolved into more massive and more biased systems at low redshift. We divide the quasar sample in luminosity and constrain the luminosity dependence of quasar bias to be db{sub Q} /dlog L = 0.20 ± 0.34 or 0.11 ± 0.32 (depending on different luminosity divisions) for quasar luminosities –23.5 > M{sub i} (z = 2) > –25.5, implying a weak luminosity dependence of clustering for luminous quasars at z-bar ∼0.5. We compare our measurements with theoretical predictions, halo occupation distribution (HOD) models, and mock catalogs. These comparisons suggest that quasars reside in a broad range of host halos. The host halo mass distributions significantly overlap with each other for quasars at different luminosities, implying a poor correlation between halo mass and instantaneous quasar luminosity. We also find that the quasar HOD parameterization is largely degenerate such that different HODs can reproduce the CCF equally well, but with different satellite fractions and host halo mass distributions. These results highlight the limitations and ambiguities in modeling the distribution of quasars with the standard HOD approach.
- OSTI ID:
- 22341970
- Journal Information:
- Astrophysical Journal, Vol. 778, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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