Thesis

Cosmological and Astrophysical applications of modified theories of gravity

• Call:

  PT-CERN Call 2021/1

• Academic Year:

  2021

• Domain:

  Astroparticle Physics

• Supervisor:

  Francisco Lobo

• Co-Supervisor:

  Pedro Avelino

• Institution:

  FCUL (Universidade de Lisboa)

• Host Institution:

  IA - Instituto de Astrofísica e Ciências do Espaço

• Abstract:

  The late-time cosmic accelerated expansion is a crucial and challenging problem in cosmology. Although the current paradigm has favored dark energy models as fundamental candidates, another possibility arises: modifications to General Relativity, introducing new degrees of freedom to the gravitational sector. We propose exploring the viability of a plethora of such models (consistently analyzing the reproduction of all the cosmological epochs) by considering generalizations of the Einstein-Hilbert action, including "quadratic Lagrangians", involving second order curvature invariants; Lagrangians which, in addition, also include couplings to the matter sector and also generalized scalar(vector)-tensor gravity theories, where scalar(vector) fields play gravitational roles that can be perceived, in an appropriate frame, as couplings to matter. The fundamental goals are to study the theoretical issues of the extra degrees of freedom and, finally, the astrophysical applications of all these classes of models, including (but not limited to) black hole solutions.