Cosmological constraints on dissipative models of inflation

We study dissipative inflation in the regime where the dissipative term takes a specific form, Gamma = Gamma(phi), analyzing two models in the weak and strong dissipative regimes with a supersymmetry breaking potential. This system introduces three new parameters: two for the potential and one for the dissipative term. After developing intuition about the predictions from these models through analytic approximations, we compute the predicted cosmological observables through full numerical evolution of the equations of motion, relating the mass scale and scale of dissipation to the characteristic amplitude and shape of the primordial power spectrum. We then use Markov chain Monte Carlo techniques to constrain a subset of the models with cosmological data from the cosmic microwave background (Wilkinson Microwave Anisotropy Probe three-year data) and large scale structure (Sloan Digital Sky Survey luminous red galaxy power spectrum). We find that the primordial dissipative parameters are uncorrelated with the 'late-time' cosmological parameters which describe the contents and expansion rate of the universe; the latter show no significant shift from the standard Lambda CDM (cold dark matter) concordance cosmology and possess close to Gaussian posterior probability distributions. In contrast, the posterior distributions of the dissipative parameters are highly non-Gaussian and their allowed ranges agree well with the expectations obtained using analytic approximations. In the weak regime, only the mass scale is tightly constrained; conversely, in the strong regime, only the dissipative coefficient is tightly constrained. A lower limit is seen on the inflation scale: a sub-Planckian inflaton is disfavored by the data. In both weak and strong regimes, we reconstruct the limits on the primordial power spectrum and show that these models prefer a red spectrum, with no significant running of the index. Despite having one extra degree of freedom in the fit compared to the standard Lambda CDM model, the data does not display a preference for any of the dissipative models; the goodness of. t is comparable to that of the latter. We calculate the reheat temperature and show that the gravitino problem can be overcome with large dissipation, which in turn leads to large levels of non-Gaussianity: if dissipative inflation is to evade the gravitino problem, the predicted level of non-Gaussianity might be seen by the Planck satellite.