Current constraints on cosmological parameters from microwave background anisotropies

We compare the latest observations of cosmic microwave background (CMB) anisotropies with the theoretical predictions of the standard scenario of structure formation. Assuming a primordial power spectrum of adiabatic perturbations we found that the total energy density is constrained to be Ωₜₒₜ=1.03±0.06 while the energy density in baryon and cold dark matter (CDM) are Ωbh²=0.021±0.03 and Ωcdmh²=0.12±0.02 (all at 68% C.L.), respectively. The primordial spectrum is consistent with scale invariance (nₛ=0.97±0.04) and the age of the universe is t₀=14.6±0.9Gyr. Adding information from large scale structure and supernovae, we found strong evidence for a cosmological constant Ω_Λ=0.70_-0.05+0.07 and a value of the Hubble parameter h=0.69±0.07. Restricting this combined analysis to flat universes, we put constraints on possible ``extensions'' of the standard scenario. A gravity waves contribution to the quadrupole anisotropy is limited to be $r<~0.42$ (95% C.L.). A constant equation of state for the dark energy component is bound to be wQ<~-0.87. We constrain the effective relativistic degrees of freedom N_ν<~6.2 and the neutrino chemical potential -0.01<~ξₑ<~0.18 and |ξ_μ,τ|<~2.3 (massless neutrinos).