3.16 Instituto de Astrofísica

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Observational constraints in Delta Gravity : CMB and supernovas
(2020) San Martín Hormazábal, Marco; Alfaro Solís, Jorge Luis; Pontificia Universidad Católica de Chile. Facultad de Física
I study the cosmological implications of Delta Gravity (DG), which is a gravitational model based on the extension of General Relativity (GR) by a new symmetry called δ ̃. In this model, new matter fields are added to the original matter fields, motivated by the additional symmetry. We call them δ ̃ matter fields. This theory predicts an accelerating Universe without introducing a Cosmological Constant Λ by hand in the equations. To test the Delta Gravity implications, I examine two critical observations in Cosmology: the rate of the Universe expansion through type Ia supernovae (SNe-Ia) and the power spectrum calculated from the cosmic microwave background radiation (CMB). To compare the observations with these model's predictions, I used a Markov Chain Monte Carlo (MCMC) analysis with the most updated SNe-Ia and Planck satellite data catalog. I obtain the fitted parameters needed to explain both SNe-Ia data and CMB measurements. I analyze the DG model's compatibility with both observations and constrain the cosmological parameters associated with the astrophysical evidence. Finally, I discuss if the Hubble Constant and the Accelerating Universe are compatible with the DG context's observational evidence.