Constraints on Cosmological Parameters from Maxima-1

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 ` in the first flight of the MAXIMA balloon-borne experiment (MAXIMA-1) and the low ` 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, Ωbh = 0.03±0.01, the physical density of cold dark matter, Ωcdmh = 0.2+0.2 −0.1, and the spectral index of primordial scalar fluctuations, ns = 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 < ΩΛ < 0.75 and 0.25 < Ωm < 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. Subject headings: cosmic microwave background — cosmology: observations — large-scale structure of universe