2016ApJ...832...70A

We present the measurement of the projected and redshift-space two-point correlation function (2pcf) of the new catalog of Chandra COSMOS-Legacy active galactic nucleus (AGN) at 2.9 <= z <= 5.5 (\langleL_bol> ∼10⁴⁶ erg s^–1) using the generalized clustering estimator based on phot-z probability distribution functions in addition to any available spec-z. We model the projected 2pcf, estimated using π_max = 200 h^–1 Mpc with the two-halo term and we derive a bias at z ∼ 3.4 equal to b = 6.6_–0.55^+0.60, which corresponds to a typical mass of the hosting halos of log M_h = 12.83_–0.11^+0.12 h^–1 M_☉. A similar bias is derived using the redshift-space 2pcf, modeled including the typical phot-z error σ_z = 0.052 of our sample at z >= 2.9. Once we integrate the projected 2pcf up to π_max = 200 h^–1 Mpc, the bias of XMM and Chandra COSMOS at z = 2.8 used in Allevato et al. is consistent with our results at higher redshifts. The results suggest only a slight increase of the bias factor of COSMOS AGNs at z >= 3 with the typical hosting halo mass of moderate-luminosity AGNs almost constant with redshift and equal to log M_h = 12.92_–0.18^+0.13 at z = 2.8 and log M_h = 12.83_–0.11^+0.12 at z ∼ 3.4, respectively. The observed redshift evolution of the bias of COSMOS AGNs implies that moderate-luminosity AGNs still inhabit group-sized halos at z >= 3, but slightly less massive than observed in different independent studies using X-ray AGNs at z <= 2.