2012MNRAS.420..514M

The clustering properties of moderate-luminosity (L_x = 10⁴¹-10⁴⁴erg/s) X-ray-selected active galactic nuclei (AGN) at z ≈ 0.1 are explored. X-ray sources in the redshift interval 0.03 < z < 0.2 are selected from a serendipitous XMM survey of the Sloan Digital Sky Survey (SDSS) footprint (XMM/SDSS) and are cross-correlated with the SDSS main galaxy sample. The inferred X-ray AGN autocorrelation function is described by a power law with amplitude r₀ ≈ 5 h^–1 Mpc and slope γ ≈ 2.0. The corresponding mass of the dark matter haloes that host X-ray AGN at z ≈ 0.1 is ≈ 10¹³h^–1M_☉. Comparison with studies at higher redshift shows that this mass scale is characteristic of moderate-luminosity X-ray AGN out to z ≈ 1. Splitting the AGN sample by rest-frame colour shows that X-ray sources in red hosts are more clustered than those associated with blue galaxies, in agreement with results at z ≈ 1. We also find that the host galaxies of X-ray AGN have lower stellar masses compared to the typical central galaxy of a dark matter halo of ≈ 10¹³h^–1M_☉. AGN hosts either have experienced less stellar mass growth compared to the average central galaxy of a halo of ≈ 10¹³ h^–1 M_☉ or a fraction of them are associated with satellite galaxies.