Warm inflation with non-comoving scalar field and radiation fluid

TL;DR

This paper explores a warm inflation model where the scalar field and radiation fluid have different velocities, leading to anisotropic evolution, and compares its predictions with Planck data to constrain model parameters.

Contribution

It introduces a novel warm inflation framework with noncomoving scalar field and radiation fluid, deriving the corresponding field equations and observational constraints.

Findings

Constraints on model parameters from Planck data

Functional forms of scalar field potentials compatible with noncomoving scenario

Analysis of weak and strong dissipation limits

Abstract

We consider a warm inflationary scenario in which the two dominant matter components present in the early Universe, the scalar field, and the radiation fluid, evolve with different four-velocities. This cosmological system is mathematically equivalent to a single anisotropic fluid, evolving with a four-velocity that is a function of the two independent fluid four-velocities. Due to the presence of the anisotropic physical parameters, the overall cosmological evolution is also anisotropic. We derive the gravitational field equations of the noncomoving scalar field-radiation mixture for a Bianchi type I geometry. By considering that the decay of the scalar field is accompanied by a corresponding radiation generation, we formulate the basic equations of the warm inflationary model in the presence of two noncomoving components. By adopting the slow roll approximation, we perform a detailed comparison of the theoretical predictions of the warm inflationary scenario with noncomoving scalar field and radiation fluid with the observational data obtained by the Planck satellite, by investigating both the weak dissipation and strong dissipation limits. Constraints on the free parameters of the model are obtained in both cases. The functional forms of the scalar field potentials compatible with the noncomoving nature of warm inflation are also derived.