Tachyonization of the $\La$CDM cosmological model

TL;DR

This paper introduces a tachyonization approach to the $ ext{Lambda}$CDM cosmological model, exploring new tachyon fields and their ability to replicate or extend standard cosmological behaviors.

Contribution

It develops new types of tachyon fields derived from the standard model and analyzes their stability, solutions, and cosmological implications, including transitions and accelerated expansion.

Findings

Standard and complementary tachyon fields reproduce $ ext{Lambda}$CDM as a limit.

Standard tachyon can model transition from acceleration to deceleration.

Phantom tachyon exhibits rapid expansion with increasing energy density.

Abstract

In this work a tachyonization of the $\Lambda$CDM model for a spatially flat Friedmann-Robertson-Walker space-time is proposed. A tachyon field and a cosmological constant are considered as the sources of the gravitational field. Starting from a stability analysis and from the exact solutions for a standard tachyon field driven by a given potential, the search for a large set of cosmological models which contain the $\Lambda$CDM model is investigated. By the use of internal transformations two new kinds of tachyon fields are derived from the standard tachyon field, namely, a complementary and a phantom tachyon fields. Numerical solutions for the three kinds of tachyon fields are determined and it is shown that the standard and complementary tachyon fields reproduces the $\Lambda$CDM model as a limiting case. The standard tachyon field can also describe a transition from an accelerated to a decelerated regime, behaving as an inflaton field at early times and as a matter field at late times. The complementary tachyon field always behaves as a matter field. The phantom tachyon field is characterized by a rapid expansion where its energy density increases with time.