Cosmological Implications of the MAXIMA-1 High-Resolution Cosmic Microwave Background Anisotropy Measurement

Abstract

We discuss the cosmological implications of the new constraints on the power spectrum of the cosmic microwave background (CMB) anisotropy derived from a new high-resolution analysis of the MAXIMA-1 measurement. The power spectrum indicates excess power at l ~ 860 over the average level of power at 411 ≤ l ≤ 785. This excess is statistically significant at the ~95% confidence level. Its position coincides with that of the third acoustic peak, as predicted by generic inflationary models selected to fit the first acoustic peak as observed in the data. The height of the excess power agrees with the predictions of a family of inflationary models with cosmological parameters that are fixed to fit the CMB data previously provided by BOOMERANG-LDB and MAXIMA-1 experiments. Our results therefore lend support for inflationary models and more generally for the dominance of adiabatic coherent perturbations in the structure formation of the universe. At the same time, they seem to disfavor a large variety of the nonstandard (but inflation-based) models that have been proposed to improve the quality of fits to the CMB data and the consistency with other cosmological observables. Within standard inflationary models, our results combined with the COBE/Differential Microwave Radiometer data give best-fit values and 95% confidence limits for the baryon density, Ω_bh² 0.033 ± 0.013, and the total density, Ω = 0.9. The primordial spectrum slope (n_s) and the optical depth to the last scattering surface (τ_c) are found to be degenerate and to obey the relation n_s (0.99 ± 0.14) + 0.46τ_c, for τ_c ≤ 0.5 (all at 95% confidence levels).