Active galactic nuclei clustering in the local universe: An unbiased picture from swift-bat

We present the clustering measurement of hard X-ray selected active galactic nuclei (AGNs) in the local universe. We used a sample of 199 sources spectroscopically confirmed, detected by Swift-BAT in its 15-55 keV all-sky survey. We measured the real space projected autocorrelation function (ACF) and detected a signal significant on projected scales lower than 200 Mpc h^-1. We measured a correlation length of r₀ = 5.56_-0.43^+0.49 Mpc h^-1 and a slope γ = 1.64_-0.07^-0.08. We also measured the ACF of Type I and Type II AGNs and found higher correlation length for Type I AGNs. We have a marginal evidence of luminosity dependent clustering of AGNs, as we detected a larger correlation length of luminous AGNs than that of low-luminosity sources. The corresponding typical host dark matter halo masses of Swift-BAT are ∼ log(M_DMH)∼ 12-14 h^-1M/M_⊙, depending on the subsample. For the whole sample, we measured log(M_DMH)∼ 13.15 h^-1M/M_⊙ which is the typical mass of a galaxy group.We estimated that the local AGN population has a typical lifetime τ_AGN ∼0.7 Gyr, it is powered by supermassive black hole with mass M_BH∼ (1-10) × 10⁸ M_⊙ and accreting with very low efficiency, log(∈)∼ -2.0. We also conclude that local AGN host galaxies are typically red-massive galaxies with stellar mass of the order (2-80) × 10¹⁰ h^-1M_⊙.We compared our results with clustering predictions of merger-driven AGN triggering models and found a good agreement.