Clustering of intermediate-luminosity x-ray-selected active galactic nuclei at z similar to 3

Abstract

We present the first clustering results of X-ray-selected active galactic nuclei (AGNs) at z similar to 3. Using Chandra X-ray imaging and UVR optical colors from MUSYC photometry in the Extended Chandra Deep Field-South field, we selected a sample of 58 z similar to 3 AGN candidates. From the optical data we also selected 1385 luminous blue galaxies (LBGs) at 2.8 < z < 3.8 with R < 25.5. We performed autocorrelation and cross-correlation analyses, and here we present results for the clustering amplitudes and dark matter (DM) halo masses of each sample. For the LBGs we find a correlation length of r(0,LBG) = 6.7 +/- 0.5 Mpc, implying a bias value of 3.5 +/- 0.3 and DM halo masses of log(M-min/M-circle dot) = 11.8 +/- 0.1. The AGN-LBG cross-correlation yields r(0,AGN-LBG) = 8.7 +/- 1.9 Mpc, implying for AGNs at 2.8 < z < 3.8 a bias value of 5.5 +/- 2.0 and DM halo masses of log(M-min/M-circle dot) = 12.6(-0.8)(+0.5). Evolution of DM halos in the Lambda CDM cosmology implies that today these z similar to 3 AGNs are found in high-mass galaxies with a typical luminosity of 7(-2)(+4)L*.