Acoustic peaks and dips in the CMB power spectrum: observational data and cosmological constraints

Abstract

The locations and amplitudes of three acoustic peaks and two dips in the last releases of the Boomerang, MAXIMA and DASI measurements of the cosmic microwave background (CMB) anisotropy power spectra as well as their statistical confidence levels are determined in a model-independent way. It is shown that the Boomerang-2001 data (Netterfield et al. 2001) fixes the location and amplitude of the first acoustic peak at more than 3\sigma confidence level. The next two peaks and dips are determined at a confidence level above 1\sigma but below 2\sigma. The locations and amplitudes of the first three peaks and two dips are 212+/-17, 5426+/-1218\mu K^2, 544+/-56, 2266+/-607\mu K^2, 843+/-35, 2077+/-876\mu K^2, 413+/-50, 1960+/-503\mu K^2, 746+/-89, 1605+/-650\mu K^2 respectively (1\sigma errors include statistical and systematic errors). The MAXIMA and DASI experiments give similar values for the extrema which they determine. The determined cosmological parameters from the CMB acoustic extrema data show good agreement with other determinations, especially with the baryon content as deduced from standard nucleosynthesis constraints. These data supplemented by the constraints from direct measurements of some cosmological parameters and data on large scale structure lead to a best-fit model which agrees with practically all the used experimental data within 1\sigma. The best-fit parameters are: \Omega_{\Lambda}=0.64^{+0.14}_{-0.27}, \Omega_{m}= 0.36^{+0.21}_{-0.11}, \Omega_b=0.047^{+0.093}_{-0.024}, n_s=1.0^{+0.59}_{-0.17}, h=0.65^{+0.35}_{-0.27} and \tau_c=0.15^{+0.95}_{-0.15} (plus/minus values show 1\sigma upper/lower limits obtained by marginalization over all other model parameters). The best-fit values of \Omega_{\nu} and T/S are close to zero, their 1\sigma upper limits are 0.17 and 1.7 respectively.