Exploring Teleparallel Dark Energy

In the present thesis we study the cosmological dynamics of the dark energy component of the Universe in the context of the Teleparallel Equivalent of General Relativity, also known as Teleparallel Gravity. It has been proposed recently the existence of a nonminimal coupling between a scalar field (quintessence or tachyon) and gravity in the framework of Teleparallel Gravity, motivated by similar constructions in the context of General Relativity. By generalizing and studying the dynamics of these models, we find interesting and viable cosmological solutions. Then we propose a new model in which the four-derivative of the scalar field of dark energy is nonminimally coupled to vector torsion. This kind of coupling is grounded on the fact that in Teleparallel Gravity a scalar field as a particle of spin zero couples to torsion through its four-derivative, which is a vector field. Differently from the old teleparallel dark energy scenario, this new model is conceptually consistent with the precepts of Teleparallel Gravity, and has no equivalent in the General Relativity context.