[[UTAPwiki/セミナー/初期宇宙・相対論速報]] Speaker: Atsuhisa Ota (Tokyo Tech) Title: Secondary isocurvature perturbations from acoustic reheating Abstract: We discuss the secondary isocurvature perturbations from mode coupling effects called acoustic reheating in the Thomson scattering dominant universe. The perfect fluid approximation for the photon energy momentum tensor is invalid deep inside the horizon so that shear viscosity and thermal conduction occur. They produce the deviations from the ideal Planck distribution, which can be recast into the entropy perturbation on superhorizon scales. We also show that the latter effect breaks the conservation law for the photon energy momentum tensor because there exists heat conduction from the baryon sector. Therefore, the superhorizon isocurvature perturbations are generated at second order. #This seminar is based on our recent work; arXiv:1705.05196. &br; |