Constraints on Cosmological Parameters from Current CMB Data

Abstract

We discuss the constraints one can place on cosmological parameters using current cosmic microwave background data. A standard $χ^2$--minimization over band--power estimates is first presented, followed by a discussion of the more correct likelihood approach. We propose an approximation to the complete likelihood function of an arbitrary experiment requiring only limited and easily found information about the observations. Examination of both open models -- $(Ω,h,Q,n)$ -- and flat models ($Ω+Ω_Λ=1$) -- $(Ω,Ω_b,h,Q,n)$ -- leaves one rather robust result: models with small curvature are favored.