The Evolution of Universe with th B-I Type Phantom Scalar Field

TL;DR

This paper explores a nonlinear Born-Infeld type phantom scalar field model that explains the universe's accelerated expansion, identifies conditions for late-time attractors, and demonstrates the model's consistency with current cosmological observations.

Contribution

It introduces a novel nonlinear scalar field Lagrangian and analyzes its cosmological implications, including conditions for late-time acceleration and stability.

Findings

The model can explain late-time acceleration with w ≤ -1.

The phantom field survives until today without disrupting nucleosynthesis.

The universe avoids future collapse under this model.

Abstract

We considered the phantom cosmology with a lagrangian $\displaystyle L=\frac{1}{\eta}[1-\sqrt{1+\eta g^{\mu\nu}\phi_{, \mu}\phi_{, \nu}}]-u(\phi)$, which is original from the nonlinear Born-Infeld type scalar field with the lagrangian $\displaystyle L=\frac{1}{\eta}[1-\sqrt{1-\eta g^{\mu\nu}\phi_{, \mu}\phi_{, \nu}}]-u(\phi)$. This cosmological model can explain the accelerated expansion of the universe with the equation of state parameter $w\leq-1$. We get a sufficient condition for a arbitrary potential to admit a late time attractor solution: the value of potential $u(X_c)$ at the critical point $(X_c,0)$ should be maximum and large than zero. We study a specific potential with the form of $u(\phi)=V_0(1+\frac{\phi}{\phi_0})e^{(-\frac{\phi}{\phi_0})}$ via phase plane analysis and compute the cosmological evolution by numerical analysis in detail. The result shows that the phantom field survive till today (to account for the observed late time accelerated expansion) without interfering with the nucleosynthesis of the standard model(the density parameter $\Omega_{\phi}\simeq10^{-12}$ at the equipartition epoch), and also avoid the future collapse of the universe.