The Age of the Universe and the Cosmological Constant Determined from Cosmic Microwave Background Anisotropy Measurements

If Omega_tot = 1 and structure formed from adiabatic initial conditions then the age of the Universe, as constrained by measurements of the cosmic microwave background (CMB), is t_0=14.0 +/- 0.5 Gyr. The uncertainty is surprisingly small given that CMB data alone constrain neither h nor Omega_Lambda significantly. It is due to the tight (and accidental) correlation, in these models, of the age with the angle subtended by the sound horizon on the last--scattering surface and thus with the well-determined acoustic peak locations. If we assume either the HST Key Project result h = 0.72 \pm .08 or simply that h > 0.55, we find Omega_Lambda > 0.4 at 95% confidence--another argument for dark energy, independent of supernovae observations. Our analysis is greatly simplified by the Monte Carlo Markov chain approach to Bayesian inference combined with a fast method for calculating angular power spectra.Comment: 5 pages, including 2 figures and one table final published versio

Recovering the Inflationary Potential and Primordial Power Spectrum With a Slow Roll Prior: Methodology and Application to WMAP 3 Year Data

We introduce a new method for applying an inflationary prior to a cosmological dataset that includes relations between observables at arbitrary order in the slow roll expansion. The process is based on the inflationary flow equations, and the slow roll parameters appear explicitly in the cosmological parameter set. We contrast our method to other ways of imposing an inflationary prior on a cosmological dataset, and argue that this method is ideal for use with heterogeneous datasets. In particular, it would be well suited to exploiting any direct detection of fundamental tensor modes by a BBO-style mission. To demonstrate the practical use of this method we apply it to the WMAPI+All dataset, and the newly released WMAPII dataset on its own and together with the SDSS data. We find that all basic classes of single field inflationary models are still allowed at the 1-2sigma level, but the overall parameter space is sharply constrained. In particular, we find evidence that the combination of WMAPII+SDSS is sensitive to effects arising from terms that are quadratic in the two leading-order slow roll parameters.Comment: v2 adds references and fixes typos. New explanatory material added clarifying effects that depend on terms that are second order in the slow roll parameters, and the impact of the beam parametrization and SZ prior on the central value of n_s v3: Added refs, minor clarifications, title modified. In press with JCAP v4: New figures, with minor smoothing artifacts removed. Matches published version. v5 Fixed typo in caption of Figure