We present the results of analysis of constraints on cosmological parameters from cosmic microwave background ( CMB ) alone and in combination with galaxy cluster baryon fraction assuming inflation–generated adiabatic scalar fluctuations .
The CMB constraints are obtained using our likelihood approximation method ( Bartlett et al. , 2000 , Douspis et al. , 2001 ) .
In the present analysis we use the new data coming from MAXIMA and BOOMERanG balloon borne experiments , the first results of the DASI interferometer together with the COBE/DMR data .
The quality of these independent data sets implies that the C _ { \ell } are rather well known , and allow reliable constraints .
We found that the constraints in the \Omega - H _ { 0 } plane are very tightened , favouring a flat Universe , that the index of the primordial fluctuations is very close to one , that the primordial baryon density is now in good agreement with primordial nucleosynthesis .
Nevertheless degeneracies between several parameters still exist , and for instance the constraint on the cosmological constant or the Hubble constant are very weak , preferred values being low .
A way to break these degeneracies is to “ cross-constrain ” the parameters by combining with constraints from other independent data .
We use the baryon fraction determination from X–ray clusters of galaxies as an additional constraint and show that the combined analysis leads to strong constraints on all cosmological parameters .
Using a high baryon fraction ( \sim 15 \% for h = 0.5 ) we found a rather low Hubble constant , values around 80 km/s/Mpc being ruled out .
Using a recent and low baryon fraction estimation ( \sim 10 \% for h = 0.5 ) we found a preferred model with a low Hubble constant and a high density content ( \Omega _ { m } ) , an Einstein–de Sitter model being only weakly ruled out .