| Clustering of high-redshift (z >= 2.9) quasars from the sloan digital sky survey (2007) | |||||||||||||||
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Abstract | |||||||||||||||
| We 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 (r) ¼ (r/r0) , the fitted parameters in comoving coordinates are r0 ¼ 15:2 2:7 h 1 Mpc and ¼ 2:0 0:3, over a scale range 4 h 1 Mpc rp 150 h 1 Mpc. Thus highredshift 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 ¼ 2:0, we find a correlation length of r0 ¼ 16:9 1:7 h 1 Mpc for the former and r0 ¼ 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 4Y50 Myr for quasars with 2:9 z 3:5, and 30Y600 Myr for quasars with z 3:5. The corresponding duty cycles are 0.004Y0.05 for the lower redshift bin and 0.03Y0.6 for the higher redshift bin. The minimum mass of halos in which these quasars reside is (2Y3) ; 1012 h 1 M for quasars with 2:9 z 3:5 and (4Y6) ; 1012 h 1 M for quasars with z 3:5; the effective bias factor beA increases with redshift, e.g., beA 8 at z ¼ 3:0 and beA 16 at z ¼ 4:5. | |||||||||||||||
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