Dynamical Analysis of the Dirac-Born-Infeld Type of Tachyon Field Minimally Coupled with Barotropic Fluid Using EOS Parametrization of a Field

Abstract

The problem of late-time cosmic acceleration is one of the critical issues in the scientific community. Various theoretical models that predict the acceleration in the late time phase have been presented. Out of these models, the non-canonical scalar field models have gained lots of popularity in recent years. The tachyon field model is one of these models that has been studied in detail by adopting the dynamical stability techniques. Usually, the dynamics of the tachyon field coupled with barotropic fluid minimally or non-minimally are studied by considering some form of field potential. With this conventional approach, there exists a variety of choices of the form of potential, which gives rise to similar dynamics. As a result, it is hard to distinguish one form of potential from another. This study focuses on the dynamics of the tachyon field (canonical and phantom) coupled minimally with barotropic fluid by choosing some parametrization of the equation of state (Eos) of the tachyon field ref. arXiv:2208.10352. These parameterized equations of states have standard forms and are time-dependent. One case is the Taylor series expansion of the Eos near the present time, which shows some severe cosmological limitations in phase space dynamics. The other parameterized equation of state is Hubble parameter-dependent and resembles the dark energy equation of state when the Hubble parameter becomes constant. In contrast, the other proposed Eos parametrization produces stable phase space dynamics in the late-time cosmic acceleration phase.