Cosmology from XMM High-Z AGN Clustering

We review the high-redshift X-ray selected AGN clustering, based on the XMM/2dF survey, and compare it with other recent XMM-based results. Using the recent Hasinger et al. (2005) and La Franca et al. (2005) luminosity functions we find that the spatial clustering lengths, derived using Limber's inversion equation, are $\sim 17$ and 20 $h^{-1}$ Mpc for the soft and hard band sources while their median redshifts are ${\bar z}\sim 1.2$ and 0.8, respectively. The corresponding bias factors at $z=\bar{z}$ are $\sim 5.3\pm 0.9$ and $\sim 5.1\pm1.1$, respectively. Within the framework of a flat cosmological model we find that our results support a model with $\Omega_m \simeq 0.26$, $\sigma_8\simeq 0.75$, $h\simeq 0.72$, w$\simeq -0.9$ (in excellent agreement with the 3 year WMAP results). We also find the present day bias of X-ray AGNs to be $b_{\circ}\sim 2$.