A Survey For Quasars With Redshifts Greater Than Four

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ISBN 13 :
Total Pages : 21 pages
Book Rating : 4.:/5 (871 download)

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Download or read book Clustering of High Redshift (z]2.9) Quasars from the Sloan Digital Sky Survey written by and published by . This book was released on 2006 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the two-point correlation function of a uniformly selected sample of 4,428 optically selected luminous 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 w{sub p}(r{sub p}) to marginalize over redshift space distortions and redshift errors. For a real-space correlation function of the form [zeta](r) = (r/r0){sup -[gamma]}, the fitted parameters in comoving coordinates are r0 = 15.2 ± 2.7 h−1 Mpc and [gamma] = 2.0 ± 0.3, over a scale range 4 ≤ r{sub p} ≤ 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 {gamma} = 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 x 1012 h−1 M{sub {circle_dot}} for quasars with 2.9 ≤ z ≤ 3.5 and 4-6 x 1012 h−1 M{sub {circle_dot}} for quasars with z ≥ 3.5; the effective bias factor b{sub eff} increases with redshift, e.g., b{sub eff} ≈ 8 at z = 3.0 and b{sub eff} ≈ 16 at z = 4.5.