We put constraints on the main cosmological parameters of different spatially flat cosmological models by combining the recent clustering results of XMM- Newton soft ( 0.5-2 keV ) X-ray sources , which have a redshift distribution with median redshift z \sim 1.2 , and SNIa data .
Using a likelihood procedure we find that the model which best reproduces the observational data and that is consistent with stellar ages is the concordance \Lambda CDM model with : \Omega _ { m } \simeq 0.28 , w \simeq - 1 , H _ { \circ } \simeq 72 km s ^ { -1 } Mpc ^ { -1 } , t _ { \circ } \simeq 13.5 Gyr and has an X-ray AGN clustering evolution which is constant in physical coordinates .
For a different clustering evolution model ( constant in comoving coordinates ) we find another viable model , although less probable due to the smaller age of the Universe , with \Omega _ { m } \simeq 0.38 , w \simeq - 1.25 , H _ { \circ } \simeq 70 km s ^ { -1 } Mpc ^ { -1 } and t _ { \circ } \simeq 12.9 Gyr .