Phantom-Like Behavior in Modified Teleparallel Gravity

Abstract

The recent data from Planck2018 shows that the equation of state parameter of effective cosmic fluid today is w0=-1.03±0.03. This indicates that it is possible for the universe to be in a phantom dominated era today. While a phantom field is essentially capable of explaining this observation, it suffers from some serious problems such as instabilities and violation of the null energy condition. So, it would be interesting to realize this effective phantom behavior without adopting a phantom field. In this paper, we study possible realization of an effective phantom behavior in modified teleparallel gravity. We show that modified teleparallel gravity is able essentially to realize an effective phantom-like behavior in the absence of a phantom field. For this purpose, we choose some observationally viable f(T) functions and prove that there are some subspaces of the models parameter space capable of realizing a phantom-like behavior without adopting a phantom field.