Structure Formation in Non-singular Higher Curvature Cosmology

TL;DR

This paper introduces a non-singular higher curvature cosmological model inspired by string theory, proposing new structure formation scenarios that align with observations and can produce primordial supermassive blackholes.

Contribution

It presents novel structure formation mechanisms within a non-singular higher curvature cosmology, incorporating string theory motivated $R^2$ scalar couplings, with explicit examples matching current observations.

Findings

Structures formed from adiabatic perturbations during chaotic inflation.

Isocurvature non-Gaussian perturbations from superinflating era.

Potential to generate primordial supermassive blackholes.

Abstract

We propose novel structure formation scenarios based on a non-singular higher curvature cosmological model. The model is motivated by the $R^2$ coupling of a scalar field appearing in the string theory, and in our scenarios the universe has no beginning and no end. We give two examples with explicit parameter values which are consistent with present observations of the cosmological structure. In the first example, the origin of structures are generated as the adiabatic perturbation during the chaotic inflation, while in the second the isocurvature non-Gaussian perturbation from the superinflating era is responsible for the structure. In the second case it is possible to generate primordial supermassive blackholes whose scale is comparable to what is expected in the galactic nuclei.