Cosmological Parameter Extraction from the First Season of Observations with DASI

Abstract

The Degree Angular Scale Interferometer (\dasi) has measured the power spectrum of the Cosmic Microwave Background anisotropy over the range of spherical harmonic multipoles 100<l<900. We compare this data, in combination with the COBE-DMR results, to a seven dimensional grid of adiabatic CDM models. Adopting the priors h>0.45 and 0.0<=tau_c<=0.4, we find that the total density of the Universe Omega_tot=1.04+/-0.06, and the spectral index of the initial scalar fluctuations n_s=1.01+0.08-0.06, in accordance with the predictions of inflationary theory. In addition we find that the physical density of baryons Omega_b.h^2=0.022+0.004-0.003, and the physical density of cold dark matter Omega_cdm.h^2=0.14+/-0.04. This value of Omega_b.h^2 is consistent with that derived from measurements of the primordial abundance ratios of the light elements combined with big bang nucleosynthesis theory. Using the result of the HST Key Project h=0.72+/-0.08 we find that Omega_t=1.00+/-0.04, the matter density Omega_m=0.40+/-0.15, and the vacuum energy density Omega_lambda=0.60+/-0.15. (All 68% confidence limits.)