Cosmological Models in Modified f(R) Gravity Theories

Abstract

The actual accelerated expansion of the universe continues being a mystery in physics. Some models had been proposed for this explanations, among them the dark energy, which however has problems of experimental character as well as theoretical. Other approximations, like modified gravity theories are an interesting alternative for this problem. Motivated in this approach we study cosmological models in f(R) theories which are natural extension of General Relativity with arbitrary functions of the Ricci scalar. One chapter has dedicated to obtain the modified field equations in the metric formalism of f(R) theories, including the discussion about boundary terms in the action. Later, we apply these equations in order to describe the dynamics of the universe, using for this as space-time, the FLRW universe. We focus our study in the problem of cosmological distances in f(R) theories. From the study of the Geodesic Deviation Equation (GDE) in this modified scenario, we obtain differential equations for the angular diameter distance, and as an extension, the Dyer-Roeder like equation in f(R) gravity.

M.Sc. Thesis (in Spanish) defended at Universidad Nacional de Colombia (Bogotá, Colombia, April - 2011). 124 pages

References in corpus (23)

• Dynamics of dark energy
• Disappearing cosmological constant in f(R) gravity
• Extended Theories of Gravity and their Cosmological and Astrophysical Applications
• Conditions for the cosmological viability of f(R) dark energy models
• The Large Scale Structure of f(R) Gravity
• Measuring the dark side (with weak lensing)
• Solar System constraints to general f(R) gravity
• The Newtonian Limit of F(R) gravity
• Solar system and equivalence principle constraints on f(R) gravity by chameleon approach
• Matter density perturbations and effective gravitational constant in modified gravity models of dark energy
• Dark Energy and Dark Gravity
• Matter instability in modified gravity
• Stability of Cosmological Solution in f(R) Models of Gravity
• The evolution of density perturbations in f(R) gravity
• Density perturbations in f(R) gravity theories in metric and Palatini formalisms
• The existence of relativistic stars in f(R) gravity
• Modified gravity as an alternative for Lambda-CDM cosmology
• Dark matter and dark energy as a effects of Modified Gravity
• The Cauchy problem of f(R) gravity
• 6+1 lessons from f(R) gravity
• f(R) gravity: successes and challenges
• Geodesic Congruences in the Palatini f(R) Theory
• Covariant Linear Perturbation Formalism