Bianchi type-I cosmology in f ( R , T ) gravity
- PDF / 245,134 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 96 Downloads / 197 Views
UCLEI, PARTICLES, FIELDS, GRAVITATION, AND ASTROPHYSICS
Bianchi TypeI Cosmology in f(R, T) Gravity1 M. F. Shamir Department of Sciences and Humanities, National University of Computer and Emerging Sciences, Lahore Campus, Pakistan email: [email protected] Received March 11, 2014
Abstract—We investigate the exact solutions of a Bianchi typeI space–time in the context of f(R, T) gravity [1], where f(R, T) is an arbitrary function of the Ricci scalar R and the trace of the energy–momentum tensor T. For this purpose, we find two exact solutions using the assumption of a constant deceleration parameter and the variation law of the Hubble parameter. The obtained solutions correspond to two different models of the Universe. The physical behavior of these models is also discussed. DOI: 10.1134/S1063776114070073 1
1. INTRODUCTION
The most popular issue in the modernday cosmol ogy is the current expansion of the Universe. It is now evident from observational and theoretical facts that our universe is in the phase of accelerated expansion [2–10]. The phenomenon of dark energy and dark matter is another topic of discussion [11–18]. It was Einstein who first proposed the concept of dark energy and introduced a small positive cosmological con stant. But after some time, he referred to it as the big gest mistake in his life. However, it is now believed that the cosmological constant may be a suitable candidate for dark energy. Another proposal to justify the current expansion of the Universe comes from modified or alternative theories of gravity. The f(T) theory of grav ity is one such example that has been recently devel oped. This theory is a generalized version of teleparal lel gravity in which the Weitzenböck connection is used instead of the LeviCivita connection. The inter esting feature of the theory is that it may explain the current acceleration without involving dark energy. A considerable amount of work has been done in this theory so far [19]. Another interesting modified theory is the f(R) theory of gravity involving a general func tion of the Ricci scalar in the standard Einstein–Hil bert Lagrangian. Some review articles [20] can be helpful in understanding the theory. Many authors have investigated f(R) gravity in dif ferent contexts [21–34]. Spherically symmetric solu tions are most commonly studied solutions due to their closeness to Nature. Vacuum and perfect fluid solutions of a spherically symmetric spacetime in the metric version of this theory were explored in [35]. They used the assumption of a constant scalar curva ture and found that the solutions corresponded to the already existing solutions in general relativity (GR). Noether symmetries have been used in [36] to study 1 The article is published in the original.
spherically symmetric solutions in f(R) gravity. Simi larly, many interesting results have been found using spherical symmetry in f(R) gravity [37]. Cylindrically symmetric vacuum and nonvacuum solutions have also been explored in this theory [38]. Plane symmet ric s
Data Loading...
