Primordial features from ekpyrotic bounces

TL;DR

This paper explores how ekpyrotic bouncing cosmologies can produce primordial features in the scalar power spectrum, potentially matching observations and offering an alternative to inflationary models.

Contribution

It demonstrates for the first time that ekpyrotic scenarios can generate specific primordial features similar to those in inflationary models.

Findings

Ekpyrotic models can produce features in the power spectrum.

Bouncing scenarios with attractor solutions are viable for feature generation.

Ekpyrotic scenarios can match observational data on primordial features.

Abstract

Certain features in the primordial scalar power spectrum are known to improve the fit to the cosmological data. We examine whether bouncing scenarios can remain viable if future data confirm the presence of such features. In inflation, the fact that the trajectory is an attractor permits the generation of features. However, bouncing scenarios often require fine tuned initial conditions, and it is only the ekpyrotic models that allow attractors. We demonstrate, for the first time, that ekpyrotic scenarios can generate specific features that have been considered in the context of inflation.