Estudo de algumas soluções obtidas teorias f(R)

Abstract

The fact that the universe is expanding with acceleration and that only 5% of its content of matter is baryonic suggests, in principle, the possibility of new alternatives to Einstein’s theory of gravity, as proposed throught the last years. Among them, the so called f(R) theories received a great deal of attention. In this dissertation, we will present these theories in two main formulations and study some solutions, specially, the spherical and axially symmetrical ones. Our aim is to show that such f(R) theories do not satisfy the observational constraints related to the solar system, and as a consequence of this, are not good candidates to substitute Einstein’s theory of gravity. Their results, however, are important to increase our knowledge related to alternative gravitational theories. We will also consider a solution which corresponds to a global monopole in f(R), and apply a method due to Newman and Janis to construct the corresponding solution, with rotation.