Abstract

We present the first clustering results of X-ray-selected active galactic nuclei (AGNs) at z ? 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 ? 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 ? = 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 ?) = 12.6 +0.5 -0.8. Evolution of DM halos in the LCDM cosmology implies that today these z ? 3 AGNs are found in high-mass galaxies with a typical luminosity of 7 +4 -2L *. © 2008. The American Astronomical Society.