Banca de DEFESA: LAZARO LIMA DE SALES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : LAZARO LIMA DE SALES
DATA : 13/07/2023
HORA: 14:00
LOCAL: Sala Virtual
TÍTULO:

Non-Gaussian Effects in Cosmology and Gravitation, Determination of Primordial Plasma Acceleration and Evolution of Chemical Potentials During Recombination

PALAVRAS-CHAVES:

Saha ionization; Tsallis statistics; Rindler space-time; Primordial Universe.

PÁGINAS: 157
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Astronomia
SUBÁREA: Astrofísica Extragalactica
ESPECIALIDADE: Cosmologia
RESUMO:

This thesis aims to revisit and innovate the understanding of some phenomena of the primordial Universe from a non-Gaussian perspective. The research is divided into three main topics: non-Gaussian effects in Big Bang nucleosynthesis, hydrogen recombi- nation, particle-antiparticle excess, and Rindler space; primordial plasma acceleration; and evolution of primordial chemical potentials. In the first topic, we determined the non-Gaussian Saha ionization equation for recombination. We defined new binding energy and established new chemical equilibrium conditions. As an application in cosmology, we showed that there is a value q ≠ 1 that provides the same result as the usual case for the nucleosynthesis temperature and the fractional ionization equi- librium temperature, and that recombination necessarily occurs in excited states in a non-Gaussian context. Furthermore, we developed a correction strategy for the Saha ionization equation, allowing the reproduction of the same results for recombination as predicted by the Boltzmann kinetic approach. We derived non-Gaussian expressions for the particle-antiparticle excess in relativistic and non-relativistic limits and analyzed their effects. As an application in gravitation, we showed that the non-Gaussian binding energy in Rindler space has a quadratic dependence on the gravitational field and derived a constraint for this field. Besides, we demonstrated that photoionization and pair production are more intensely suppressed in regions with strong gravitational fields compared to results obtained with classical statistics and derived a constraint im- posed on the electron and positron chemical potentials. Regarding the second topic, we determined the plasma acceleration via the Saha ionization equation in the primordial Universe. We derived the plasma acceleration at the beginning of nucleosynthesis and showed that there is a transition in acceleration around the nucleosynthesis temperature. We also demonstrated that when the deuterium bottleneck is overcome, the plasma acceleration is much higher than the acceleration of the Universe. We showed that the plasma acceleration is negative at the time of recombination, and for z < 380.23 the primordial plasma begins to accelerate. We investigated the possible physical reasons underlying this occurrence. Finally, in the third topic, we revisited the hydrogen recom- bination history from an innovative perspective: the evolution of chemical potentials. We derived expressions for these potentials, which are dependent on the thermal bath temperature and the ionization degree of the Universe. This novel approach revealed a constraint between the chemical potentials of hydrogen and the proton at z ≈ 1200, when the free electron fraction is Xe ≈ 1/3.

MEMBROS DA BANCA:
Presidente - 6076 - FÁBIO CABRAL CARVALHO
Interna - 8072 - MARIA ALDINÊZ DANTAS
Interno - 721.063.104-63 - RAIMUNDO SILVA JÚNIOR - UFRN
Externo à Instituição - RAFAEL DA COSTA NUNES - UFRGS
Externo à Instituição - CARLOS ALEXANDRE WUENSCHE DE SOUZA - INPE