Production of Primordial Gravitational Waves in Teleparallel Gravity

We study the production of primordial gravitational waves in the context of extended teleparallel gravity models and compare them with those of general relativity. Teleparallel gravity has been widely studied in the context of the late universe but not much in the early universe. Two sources of primordial gravitational waves are considered, vacuum fluctuations and tensor anisotropies within two inflation-compatible backgrounds: a perfect de Sitter and a quasi de Sitter background. We find that in the vacuum case with a perfect de Sitter background, the gravitational waves propagation equation is the same as that of general relativity, however, if the background is promoted to a quasi de Sitter background, the propagation equations are different resulting in an important difference on the tensor spectral index. When tensor anisotropies are included, we compute the most general solution for gravitational waves in terms of a retarded Green's function and analyze the contributions to the power spectrum from these anisotropies. Finally, we investigate the energy density of these gravitational waves.Comment: 21 pages. Version accepted in Physics of the Dark Univers

Stability analysis for cosmological models in f (T, B) gravity

In this paper we study cosmological solutions of the f (T, B) gravity using dynamical system analyses. For this purpose, we consider cosmological viable functions of f (T, B) that are capable of reproducing the dynamics of the Universe. We present three specific models of f (T, B) gravity which have a general form of their respective solutions by writing the equations of motion as an autonomous system. Finally, we study its hyperbolic critical points and general trajectories in the phase space of the resulting dynamical variables which turn out to be compatible with the current late-time observations.peer-reviewe

On primordial gravitational waves in Teleparallel Gravity

Teleparallel Gravity is a gauge theory where gravity is a manifestation of the torsion of space-time and its success relies on being a possible solution to some problems of General Relativity. In this essay we introduce the construction of the theory by defining its geometrical setup, and how we can build it as a gauge theory of translations locally invariant under the Lorentz group. In this context, we will study the production of primordial gravitational waves and the observational implications when extended models are taken into account, particularly, we will notice how the tensor spectral index changes and produces a direct impact on the power spectrum from vacuum fluctuations and any source of tensor anisotropic stress in comparison to General Relativity.Comment: Honorable mention for Gravity Research Foundation 2023 Awards for Essays on Gravitation. Comments welcome. 12 page