Constraining the cosmological baryon density with X-ray clusters
Abstract
We study the properties of X-ray galaxy clusters in four cold dark matter models with different baryon fraction
Ω
BM
ranging from 5 to 20 per cent. By using an original three-dimensional hydrodynamic code based on the piecewise parabolic method, we run simulations on a box with size
64
h
−1
Mpc and we identify the clusters by selecting the peaks in the X-ray luminosity field. We analyse these mock catalogues by computing the mass function, the luminosity function, the temperature distribution and the luminosity-temperature relation. By comparing the predictions of the different models to a series of recent observational results, we find that only the models with low baryonic content agree with the data, while models with larger baryon fraction are well outside the 1-
σ
errorbars. In particular, the analysis of the luminosity functions, both bolometric and in the energy band [0.5--2] keV, requires $\Omega_{BM}\mincir 0.05$ when we fix the values
h=0.5
and
n=0.8
for the Hubble parameter and the primordial spectral index, respectively. Moreover we find that, independently of the cosmological scenario, all the considered quantities have a very little redshift evolution, particularly between
z=0.5
and
z=0
.