SIMBAD references

We present detailed clustering measurements from the 2dF Quasi-Stellar Object Redshift Survey (2QZ) in the redshift range 0.8 < z < 2.1. Using a flux-limited sample of ∼14000 objects with effective redshift z_eff= 1.47, we estimate the quasar projected correlation function for separations 1 < r/h^–1 Mpc < 20. We find that the two-point correlation function in real space is well approximated by a power law with slope γ= 1.5±0.2 and comoving correlation length r₀= 4.8^+0.9_–1.5h^–1 Mpc. Splitting the sample into three subsets based on redshift, we find evidence for an increase of the clustering amplitude with look-back time. For a fixed γ, evolution of r₀is detected at the 3.6σ confidence level. The ratio between the quasar correlation function and the mass autocorrelation function (derived adopting the concordance cosmological model) is found to be scale-independent. For a linear mass-clustering amplitude σ₈= 0.8, the `bias parameter' decreases from b≃ 3.9 at z_eff= 1.89 to b≃ 1.8 at z_eff= 1.06. From the observed abundance and clustering, we infer how quasars populate dark matter haloes of different masses. We find that 2QZ quasars sit in haloes with M > 10¹² M_☉ and that the characteristic mass of their host haloes is of the order of 10¹³ M_☉. The observed clustering is consistent with assuming that the locally observed correlation between black hole mass and host galaxy circular velocity is still valid at z > 1. From the fraction of haloes which contain active quasars, we infer that the characteristic quasar lifetime is t_Q∼ afewx10⁷ yr at z∼ 1 and approaches 10⁸ yr at higher redshifts.