Accelerated expansion as manifestation of gravity: when dark energy belongs to the left

• Ano de defesa: 2020
• Autor(a) principal: Giani, Leonardo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Astrofísica, Cosmologia e Gravitação; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Astrofísica, Cosmologia e Gravitação
• Palavras-chave em Português: Teorema de Lovelock; Energia escura; Modelo VAAS; subject.br-rjbn; Astronomia
• Link de acesso: http://repositorio.ufes.br/handle/10/13987

In order to explain the Late-times accelerated expansion of the Universe we must appeal to some form of Dark Energy. In the standard model of cosmology, the latter is interpreted as a Cosmological Constant . However, for a number of reasons, a Cosmological Constant is not completely satisfactory. In this thesis we study Dark Energy models of geometrical nature, and thus a manifestation of the underlying gravitational theory. In the rst part of the thesis we will review the CDM model and give a brief classi cation of the landscape of alternative Dark Energy candidates based on the Love lock theorem. The second part of the thesis is instead devoted to the presentation of our main results on the topic of Dark Energy. To begin with, we will report our studies about nonlocal modi cations of gravity involving the differential operator 1R, with emphasis on a speci c model and on the common behavior shared by this and similar theories in the late stages of the evolution of the Universe. Then we introduce a novel class of modi ed gravity theories based on the anticurvature tensor A (the inverse of the Ricci tensor), and assess their capability as source of Dark Energy. Finally, we will discuss a type of drift e ects which we predicted in the contest of Strong Gravitational Lensing, which could be employed both to study the e ective equation of state of the Universe and to constrain violations of the Equivalence Principle.