Observational constraints and stability in viscous $f(T,\mathcal{T})$ gravity

TL;DR

This paper investigates a viscous $f(T,\,\mathcal{T})$ gravity model within a flat-FRW universe, deriving cosmological parameters, analyzing accelerated expansion, and assessing system stability through the speed of sound.

Contribution

It introduces a viscous $f(T,\,\mathcal{T})$ gravity framework and explores its implications for cosmic acceleration and stability, which is a novel extension of teleparallel gravity models.

Findings

The model predicts accelerated expansion consistent with observations.

Cosmological parameters are expressed in terms of redshift.

The system remains stable under certain conditions.

Abstract

In this paper, we study the $f(T,\mathcal{T})$ gravity model in the presence of the bulk viscosity by the flat-FRW metric. The field equation is obtained by teleparallel gravity with tetrad field. The universe components are considered as matter and dark energy which the dark energy component associates from the viscous $f(T,\mathcal{T})$ gravity. After calculating the Friedmann equations, we obtain the energy density, the pressure and the EoS of dark energy in terms of the redshift parameter. Afterward, we plot the corresponding cosmological parameters versus the redshift parameter and examine the accelerated expansion of the universe. In the end, we explore the system stability by a function called the speed sound parameter.