New Solutions of the Inflationary Flow Equations

The inflationary flow equations are a frequently used method of surveying the space of inflationary models. In these applications the infinite hierarchy of differential equations is truncated in a way which has been shown to be equivalent to restricting the set of models considered to those characterized by polynomial inflaton potentials. This paper explores a different method of solving the flow equations, which does not truncate the hierarchy and in consequence covers a much wider class of models while retaining the practical usability of the standard approach.Comment: References added, and a couple of comment

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

AIC, BIC, Bayesian evidence against the interacting dark energy model

Recent astronomical observations have indicated that the Universe is in the phase of accelerated expansion. While there are many cosmological models which try to explain this phenomenon, we focus on the interacting $\Lambda$CDM model where the interaction between the dark energy and dark matter sectors takes place. This model is compared to its simpler alternative---the $\Lambda$CDM model. To choose between these models the likelihood ratio test was applied as well as the model comparison methods (employing Occam's principle): the Akaike information criterion (AIC), the Bayesian information criterion (BIC) and the Bayesian evidence. Using the current astronomical data: SNIa (Union2.1), $h(z)$, BAO, Alcock--Paczynski test and CMB we evaluated both models. The analyses based on the AIC indicated that there is less support for the interacting $\Lambda$CDM model when compared to the $\Lambda$CDM model, while those based on the BIC indicated that there is the strong evidence against it in favor the $\Lambda$CDM model. Given the weak or almost none support for the interacting $\Lambda$CDM model and bearing in mind Occam's razor we are inclined to reject this model.Comment: LaTeX svjour3, 12 pages, 3 figure

The Search For Primordial Tensor Modes

We review the prospects for detecting tensor modes generated during inflation by CMB polarization experiments and by searching for a stochastic gravitational wave background with laser interferometers in space. We tackle the following two questions: (i) what does inflation predict for the tensor fluctuations? (ii) is it really worth building experiments that can cover only a small range of tensor amplitudes