Thesis

Acceleration of the late universe: Modified gravity theories or Back-reaction?

• Call:

  IDPASC Portugal - PHD Programme 2015

• Academic Year:

  2015 / 2016

• Domains:

  Cosmology | Astrophysics

• Supervisor:

  José Pedro Mimoso

• Co-Supervisor:

  Francisco Lobo

• Institution:

  Faculdade de Ciências - Universidade de Lisboa

• Host Institution:

  Instituto de Astrofísica e Ciencias do Espaço

• Abstract:

  The proposed research plan is aimed at explaining the observed, late acceleration of the Universe, looking beyond the standard theory of gravity, and assessing the implications of inhomogeneities of the space-time. Instead of assuming the existence of some sort of exotic matter, it focus on the approaches that consider extensions of the gravitational theory itself and the assumption of spatial inhomogeneity. The latter envisage modifications of the geometrical sector of the theory. So a possible degeneracy between the predictions arising from modified gravity theory and those of the so-called back-reaction prescription will be investigated. Ultimately this means on the one hand, thoroughly comparing both prescriptions, and, on the other hand, testing extended models both from modified gravity, and back-reaction against astrophysical and laboratory measurements, as well as laboratory and space-based Equivalence Principle experiments to put forward discriminators. The present work plan inscribes itself in the goals the Theory and Cosmological Simulations working groups of the Euclid space mission.