f (R, T) = f (R) plus λT gravity models as alternatives to cosmic acceleration

Author(s)

Sahoo, P. K. ; Moraes, P. H. R. S. ; Sahoo, Parbati ; Bishi, Binaya K.

• Document type: Journal article
• Source: EUROPEAN PHYSICAL JOURNAL C; v. 78, n. 9, p. 10-pg., 2018-09-15.

Abstract

This article presents cosmological models that arise in a subclass of f (R, T) = f(R) + f (T) gravity models, with different f (R) functions and fixed T-dependence. That is, the gravitational lagrangian is considered as f (R, T) = f (R) + lambda T, with constant lambda. Here R and T represent the Ricci scalar and trace of the stress-energy tensor, respectively. The modified gravitational field equations are obtained through the metric formalism for the Friedmann-Lemaitre-Robertson-Walker metric with signature (+,-, -, -). We work with f (R) = R + alpha R-2- mu(4)/R, f (R) = R + k ln(gamma R) and f (R) = R + me([-nR]), with alpha, mu, k, gamma, m and n all free parameters, which lead to three different cosmological models for our Universe. For the choice of lambda = 0, this reduces to widely discussed f (R) gravity models. This manuscript clearly describes the effects of adding the trace of the energy-momentum tensor in the f (R) lagrangian. The exact solution of the modified field equations are obtained under the hybrid expansion law. Also we present the Om diagnostic analysis for the discussed models. (AU)

• FAPESP's process: 15/08476-0 - Gravitational waves in f(R,T) theories: polarization states and astrophysical sources
• Grantee: Pedro Henrique Ribeiro da Silva Moraes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral