Confronting Dark Energy Models using Galaxy Cluster Number Counts

Abstract

The mass function of cluster-size halos and their redshift distribution are computed for 12 distinct accelerating cosmological scenarios and confronted to the predictions of the conventional flat $\Lambda$CDM model. The comparison with $\Lambda$CDM is performed by a two-step process. Firstly, we determine the free parameters of all models through a joint analysis involving the latest cosmological data, using SNe type Ia, the CMB shift parameter and BAO. Apart from a brane world inspired cosmology, it is found that the derived Hubble relation of theremaining models reproduce the $\Lambda$CDM results approximately with the same degree of statistical confidence. Secondly, in order to attempt distinguish the different dark energy models from the expectations of $\Lambda$CDM, we analyze the predicted cluster-size halo redshift distribution on the basis of two future cluster surveys: (i) an X-ray survey based on the {\tt eROSITA} satellite, and (ii) a Sunayev-Zeldovich survey based on the South Pole Telescope. As a result, we find that the predictions of 8 out of 12 dark energy models can be clearly distinguished from the $\Lambda$CDM cosmology, while the predictions of 4 models are statistically equivalent to those of the $\Lambda$CDM model, as far as the expected cluster mass function and redshift distribution are concerned. The present analysis suggest that such a technique appears to be very competitive to independent tests probing the late time evolution of the Universe and the associated dark energy effects.Comment: 14 pages, 3 figures, major changes, accepted for publication in Phys. Rev.