Testing a dissipative kinetic k-essence model

TL;DR

This paper investigates a kinetic k-essence cosmological model with bulk viscosity, deriving analytical solutions and constraining parameters using supernova and Hubble data to understand its viability.

Contribution

It introduces a viscous kinetic k-essence model with analytical solutions and compares its predictions with observational data for the first time.

Findings

Analytical solutions for specific parameter cases

Viscous model solutions resemble non-viscous counterparts

Best-fit parameters constrained by supernova and Hubble data

Abstract

In this work, we present a study of a purely kinetic k-essence model, characterized basically by a parameter $\alpha$ in presence of a bulk dissipative term, whose relationship between viscous pressure $\Pi$ and energy density $\rho$ of the background follows a polytropic type law $\Pi \propto \rho^{\lambda+1/2}$, where $\lambda$, in principle, is a parameter without restrictions. Analytical solutions for the energy density of the k-essence field are found in two specific cases: $\lambda=1/2$ and $\lambda=(1-\alpha)/2\alpha$, and then we show that these solutions posses the same functional form than the non-viscous counterpart. Finally, both approach are contrasted with observational data from type Ia supernova, and the most recent Hubble parameter measurements, and therefore, the best values for the parameters of the theory are founds.