1997/11/06 by F. La Franca, Fabio La Franca, P. Andreani +3 · 5 citations
Environmental Science · Mathematics · Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysics #Cluster analysis #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Mathematics #Physics #Quasar #Redshift #Remote Sensing in Agriculture #Statistics #astro-ph
paper · pdf · doi:10.1086/305508
8 pages including 2 eps figures, LaTeX (AAS v4.0), ApJ in press
arxiv created 1997/11/06 · openalex publication_date 1998/04/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The evolution of quasar clustering is investigated with a new sample of 388 quasars with 0.3 < z ≤ 2.2, B ≤ 20.5, and M B < -23, selected over an area of 24.6 deg 2 in the south Galactic pole. Assuming a two-point correlation function of the form ξ( r ) = ( r / r o ) -1.8 , we detect clustering with r 0 = 6.2 ± 1.6 h -1 comoving Mpc, and ( r =15 h -1 Mpc )=3/ r 3 ∫ 0 r x 2 ξ( x ) dx =0.52±20 at an average redshift of ⟨ z = 1.3⟩. We find a 2 σ significant increase of the quasar clustering between z = 0.95 and z = 1.8, independent of the quasar absolute magnitude and inconsistent with recent evidence on the evolution of galaxy clustering. If other quasar samples are added (resulting in a total data set of 737 quasars), the increase of the quasar clustering is still favored, although it becomes less significant. With a parameterization of the evolution of the type ξ( r , z ) = ( r / r 0 ) -γ (1 + z ) -(3-γ+ ) , we find ≃ -2.5. Evolutionary parameters > 0.0 are excluded at a 0.3% probability level, compared with ~ 0.8 found for galaxies. The observed clustering properties appear qualitatively consistent with a scenario of Ω = 1 cold dark matter in which (1) the difference between the quasar and the galaxy clustering can be explained as a difference in the effective bias and redshift distributions and (2) the quasars, with a lifetime of t ~ 10 8 yr, sparsely sample halos of mass greater than M min ~ 10 12 -10 13 h -1 M ☉ . We also discuss the possibility that the observed change in the quasar clustering is due to an increase in the fraction of early-type galaxies as quasar hosts at high z .