Constraints on Cosmological Parameters from MAXIMA-1

TL;DR

The paper uses the MAXIMA-1 CMB angular power spectrum, in combination with COBE/DMR data, to constrain a seven-dimensional parameter space under inflationary adiabatic models. A maximum-likelihood approach with grid sampling and interpolation yields tight constraints on $Ω$, $Ω_b h^2$, $Ω_{cdm} h^2$, $n_s$, and $τ_c$, and, when combined with high-redshift SN Ia data, strong evidence for a non-zero cosmological constant and a subdominant matter component. The results favor a flat geometry ($Ω$ near 1) and yield a shape parameter $Γ$ consistent with large-scale structure observations. Overall, the findings support the ΛCDM framework and demonstrate the power of CMB measurements in breaking degeneracies and constraining fundamental cosmological parameters.

Abstract

We set new constraints on a seven-dimensional space of cosmological parameters within the class of inflationary adiabatic models. We use the angular power spectrum of the cosmic microwave background measured over a wide range of \ell in the first flight of the MAXIMA balloon-borne experiment (MAXIMA-1) and the low \ell results from COBE/DMR. We find constraints on the total energy density of the universe, Ω=1.0^{+0.15}_{-0.30}, the physical density of baryons, Ω_{b}h^2=0.03 +/- 0.01, the physical density of cold dark matter, Ω_{cdm}h^2=0.2^{+0.2}_{-0.1}$, and the spectral index of primordial scalar fluctuations, n_s=1.08+/-0.1, all at the 95% confidence level. By combining our results with measurements of high-redshift supernovae we constrain the value of the cosmological constant and the fractional amount of pressureless matter in the universe to 0.45<Ω_Λ<0.75 and 0.25<Ω_{m}<0.50, at the 95% confidence level. Our results are consistent with a flat universe and the shape parameter deduced from large scale structure, and in marginal agreement with the baryon density from big bang nucleosynthesis.