Models and observables beyond the hypothesis of homogeneity of standard cosmology.

Name: Eddy Giusepe Chirinos Isidro
Type: PhD thesis
Publication date: 11/07/2019
Advisor:

Name Rolesort descending
Valerio Marra Advisor *

Examining board:

Name Rolesort descending
Valerio Marra Advisor *
Wiliam Santiago Hipolito Ricaldi External Examiner *
Armando Bartolome Bernui Leo External Examiner *
Jailson Souza de Alcaniz External Examiner *
Júlio César Fabris Internal Examiner *

Summary: In the first part of this thesis we present three works developed in the first years of my PhD. The first is based on considering an effective viscous pressure as a result of the backreaction of inhomogeneities within Buchert’s formalism. We considered an effective metric with a time-dependent radius of curvature and performed observational tests with data from Supernovae Ia and compared with other models (among them ΛCDM). In the second work, we describe, in the context of the Lemaître-Tolman-Bondi metric (LTB), two flat and inhomogeneous big bang time models. Depending on the sign of the derivative, with respect to r, of the inhomogeneous big bang time we will have a local overdensity or a local underdensity. These models are toy models, which will be fitted to supernova data. We also discuss future measurements of redshift drift as a promising tool for discriminating between inhomogeneous configurations and the standard model. In the third paper we again consider effects of cosmological backreaction within Buchert’s formalism, but this time based on an explicit solution of LTB dynamics that is linear in the curvature parameter and has an inhomogeneous big bang time. This configuration represents an exactly solvable toy model but does not adequately describe our real universe. This “inconsistency” is verified by comparing our results with supernova data and with differential age data from old galaxies (cosmic chronometers). In our last work we will describe the cosmos with modelindependent analyses. This will be possible thanks to galaxy maps that enable detailed studies on the nature of fluctuations in the density of the Universe and the formation of large scale structures. We will study the Baryon Acoustic Oscillations (BAO) scale, since it is a characteristic scale imprinted on the distribution of galaxies and cosmic background radiation (CMB), which can be used as standard rule. To find the radial BAO scale we use the recipe by E. Sánchez et al. 2013. We then perform the observational tests with data from the third phase of the Baryon Oscillation Spectroscopic Survey (BOSS) from the Sloan Digital Sky Survey (SDSS-DR12) and verified our results with simulated data from MultiDark-PATCHY DR12.

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