Cosmology Seminar

Our next cosmology seminar takes place on Friday 29th of November, seminar room E349 at 2pm. The speaker is Atsuhisa Ota from the DAMPT (Cambridge, U.K.).

At 14:00, room E349, Atsuhisa Ota (DAMPT, Cambridge), will be talking about

Induced superhorizon tensor perturbations from anisotropic non-Gaussianity

While we have not detected large scale tensor perturbations, they are essential for cosmology because we consider their origin is microscopic quantum fluctuations during inflation. However, we should note that the classical secondary effects of scalar perturbations also source them after inflation. We usually consider that these secondary effects are not significant on the CMB anisotropy scale, but we will revisit this issue with non-Gaussian initial conditions for the scalar perturbations. In this talk, we will show that induced tensor modes can be generated on superhorizon scales through the intrinsic long-short mode coupling due to the non-Gaussianity. The induced tensor power spectrum has similar scale dependence with the primordial contribution. Hence we can discuss the detectability by the CMB anisotropy measurements. Interestingly, the induced tensor perturbations can be significantly enhanced, depending on the reheating scenario. Also, we will present the observational consequences of various non-Gaussian initial conditions based on the present framework.