Cosmological perturbations in warm-tachyon inflationary universe model with viscous pressure

TL;DR

This paper explores a warm-tachyon inflation model incorporating viscous pressure, deriving conditions for realization, analyzing perturbations, and comparing predictions with recent cosmological observations.

Contribution

It introduces a novel warm-tachyon inflation model with viscous pressure, providing analytic expressions and observational constraints for the first time.

Findings

Model compatible with WMAP9, Planck, and BICEP2 data.

Derived conditions for slow-roll and high-dissipation regimes.

Analyzed two specific cases with constant and field-dependent parameters.

Abstract

We study the warm-tachyon inflationary universe model with viscous pressure in high-dissipation regime. General conditions which are required for this model to be realizable are derived in the slow-roll approximation. We present analytic expressions for density perturbation and amplitude of tensor perturbation in longitudinal gauge. Expressions of tensor-to-scalar ratio, scalar spectral index and its running are obtained. We develop our model by using exponential potential, the characteristics of this model are calculated for two specific cases in great details: 1- Dissipative parameter $\Gamma$ and bulk viscous parameter $\zeta$ are constant parameters. 2- Dissipative parameter is a function of tachyon field $\phi$ and bulk viscous parameter is a function of matter-radiation mixture energy density $\rho$. The parameters of the model are restricted by recent observational data from the nine-year Wilkinson microwave anisotropy probe (WMAP9), Planck and BICEP2 data.