Analytical primordial power spectra from a potential dominated pre-inflationary bounce in a closed universe

Abstract

The CMB TT spectrum is suppressed at large scales, a feature that may originate from pre-inflationary dynamics in a closed universe. We study the primordial power spectrum for a potential dominated pre-inflationary bounce in a spatially closed universe by extending the analytical approximations of Thavanesan et al.~\cite{Thavanesan2021}, and find that it exhibits the same suppression trend as the KICI and emergent scenarios. Using the analytical approximation, we further show that the resulting CMB TT spectra for the pre-inflationary bounce scenario are the same as those of the KICI and emergent scenarios, indicating that the pre-inflationary bounce scenario can account for the large scale suppression of the CMB TT spectrum as well as the KICI and emergent scenarios. This extends the potential independent analytical approach to a potential dominated pre-inflationary bounce, providing a new scenario that accounts for the observed large scale suppression of the CMB TT spectrum.