Yue Shen et al. 2007 The Astronomical Journal 133 2222 doi:10.1086/513517
Clustering of High-Redshift (z ≥ 2.9) Quasars from the Sloan Digital Sky Survey
FREE ISSUEYue Shen1, Michael A. Strauss1, Masamune Oguri1,2, Joseph F. Hennawi3, Xiaohui Fan4, Gordon T. Richards5, Patrick B. Hall6, James E. Gunn1, Donald P. Schneider7, Alexander S. Szalay8, Anirudda R. Thakar8, Daniel E. Vanden Berk7, Scott F. Anderson9, Neta A. Bahcall1, Andrew J. Connolly10 and Gillian R. Knapp1
Show affiliationsWe study the two-point correlation function of a uniformly selected sample of 4426 luminous optical quasars with redshift 2.9 ≤ z ≤ 5.4 selected over 4041 deg2 from the Fifth Data Release of the Sloan Digital Sky Survey. We fit a power-law to the projected correlation function wp(rp) to marginalize over redshift-space distortions and redshift errors. For a real-space correlation function of the form ξ(r) = (r/r0)-γ, the fitted parameters in comoving coordinates are r0 = 15.2 ± 2.7 h-1 Mpc and γ = 2.0 ± 0.3, over a scale range 4 h-1 Mpc ≤ rp ≤ 150 h-1 Mpc. Thus high-redshift quasars are appreciably more strongly clustered than their z ≈ 1.5 counterparts, which have a comoving clustering length r0 ≈ 6.5 h-1 Mpc. Dividing our sample into two redshift bins, 2.9 ≤ z ≤ 3.5 and z ≥ 3.5, and assuming a power-law index γ = 2.0, we find a correlation length of r0 = 16.9 ± 1.7 h-1 Mpc for the former and r0 = 24.3 ± 2.4 h-1 Mpc for the latter. Strong clustering at high redshift indicates that quasars are found in very massive, and therefore highly biased, halos. Following Martini & Weinberg, we relate the clustering strength and quasar number density to the quasar lifetimes and duty cycle. Using the Sheth & Tormen halo mass function, the quasar lifetime is estimated to lie in the range ~4-50 Myr for quasars with 2.9 ≤ z ≤ 3.5, and ~30-600 Myr for quasars with z ≥ 3.5. The corresponding duty cycles are ~0.004-0.05 for the lower redshift bin and ~0.03-0.6 for the higher redshift bin. The minimum mass of halos in which these quasars reside is (2-3) × 1012 h-1 M
for quasars with 2.9 ≤ z ≤ 3.5 and (4-6) × 1012 h-1 M for quasars with z ≥ 3.5; the effective bias factor beff increases with redshift, e.g., beff ~ 8 at z = 3.0 and beff ~ 16 at z = 4.5.
- Keywords
cosmology: observations; large-scale structure of universe; quasars: general; surveys
- Dates
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Issue 5 (2007 May)
Received 2006 November 3, accepted for publication 2007 January 30
Published 2007 April 3
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Clustering of High-Redshift (z ≥ 2.9) Quasars from the Sloan Digital Sky Survey
Yue Shen et al. 2007 The Astronomical Journal 133 2222
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