Quintessential Inflation in Palatini Gravity

TL;DR

This paper explores a model of quintessential inflation within Palatini gravity, demonstrating successful reheating and explaining dark energy as residual potential energy, consistent with recent cosmological measurements.

Contribution

It introduces a Palatini gravity-based quintessential inflation model with a small non-minimal coupling, detailing reheating processes and dark energy explanation, aligning with Planck data.

Findings

Reheating temperature ranges from 10^3 to 10^8 GeV.

Model aligns with Planck measurements.

Dark energy explained by residual potential energy.

Abstract

We study a model of quintessential inflation in the context of Palatini gravity. As a representative example, we consider the Peebles-Vilenkin model of quintessential inflation with a small non-minimal coupling to gravity, which is consistent with the most recent Planck measurements. At the end of inflation, the inflaton field passes through a tachyonic region and it leads to explosive particle production through the tachyonic preheating process. After preheating, the Universe becomes dominated by the kinetic energy of the inflaton and enters a period of kination. Eventually, the total energy density of the Universe becomes dominated by radiation, resulting in reheating. We find that the model predicts the reheating temperature values $T_{\rm{RH}} \sim \mathcal{O}(10^3 - 10^8) \, \rm{GeV}$, which is significantly above the temperature of Big Bang Nucleosynthesis. Following reheating, the inflaton field rolls down the quintessence potential until it freezes. Since the quintessence remains frozen until the present day, the residual potential energy density at this field value explains the observed dark energy density.