Reheating after S-Brane Ekpyrosis

TL;DR

This paper explores a nonsingular Ekpyrotic cosmology involving an S-brane that mediates a transition from contraction to expansion, producing scale-invariant gravitational waves and efficient reheating through gauge field decay.

Contribution

It introduces a novel reheating mechanism via gauge field production driven by S-brane decay in Ekpyrotic cosmology.

Findings

Gravitational waves acquire a scale-invariant spectrum passing through the S-brane.

Gauge field fluctuations are efficiently produced during S-brane decay.

Reheating leads to a radiation-dominated expanding universe.

Abstract

In recent work, two of us proposed a nonsingular Ekpyrotic cosmology making use of an S-brane which forms at the end of the phase of Ekpyrotic contraction. This S-Brane mediates a transition between contraction and expansion. Graviitational waves passing through the S-Brane acquire a roughly scale-invariant spectrum, and if the S-Brane has zero shear, then a roughly scale-invariant spectrum of cosmological perturbatiions results. Here, we study the production of gauge field fluctuations driven by the decay of the S-Brane, and we show that the reheating process via gauge field production will be efficient, leading to a radiation-dominated expanding phase.