http://localhost:8080/tede/handle/tede/8 2026-09-23T09:16:37Z http://localhost:8080/tede/handle/tede/223 “ESTUDO DE MODELOS DE GRAVIDADE MODIFICADA USANDO DADOS COSMOLÓGICOS DE AGLOMERAÇÃO DE MATÉRIA” Manoel Vicente de Souza Filho, Manoel Vicente de Souza Filho Armando Bartolome Bernui Leo , Armando Bartolome Bernui Leo The growth of cosmic structures is investigated through the analyses of f(z) and σ8(z) cosmic observables data, using non-parametric Gaussian Process reconstructions combined with MCMC statistical analyses. The standard flat-LCDM model, General Relativity–based extensions, and F(R) modified gravity scenarios are systematically compared in terms of statistical performance, physical consistency, and the level of tension in the S8 parameter relative to the Planck -2018 benchmark. Our results show that, while LCDM remains consistent with current data, it exhibits deviations at high redshifts. Among physically viable alternatives, the Hu–Sawicki (n = 1) model emerges as the most robust scenario, providing good agreement with observational data and compatibility with local gravity tests, while the Starobinsky (n = 2) model appears as a competitive alternative by moderately alleviating the S8 tension. Observatorio Nacional Dissertação 2026-01-20T00:00:00Z http://localhost:8080/tede/handle/tede/222 “CONSTRUINDO UMA ABRANGENTE LISTA DE LINHAS ESPECTRAIS PARA ESPECTROSCOPIA NO INFRAVERMELHO PRÓXIMO DE λ 1–5 μM” Gabriela Neves Lima, Gabriela Neves Lima Katia Maria Leite da Cunha , Katia Maria Leite da Cunha Spectral line lists constitute the foundation for spectral synthesis calculations and the determination of chemical abundances, including those derived from large spectroscopic surveys such as SDSS–APOGEE. This project extended beyond the APOGEE spectral region (between λ 1.5 and 1.7, μm) and produced a new and comprehensive atomic and molecular line list covering the wavelength range λ 1 to 5, μm. Currently available atomic and molecular data were critically reviewed and consolidated into an updated line list, spanning a spectral range compatible with several combinations of ground-based telescopes and spectrographs, as well as with the NIRSpec spectrograph aboard the James Webb Space Telescope. The line list was constructed in the format accepted by the spectral synthesis code Turbospectrum, which was used to generate the synthetic spectra employed for comparison with the observed spectra. The atomic and molecular data were evaluated through comparisons with the benchmark stars the Sun, Arcturus, and an M dwarf with previously determined parameters, using high-quality, high-resolution near-infrared spectra. The inclusion of an M-type dwarf star in the fitting and validation processes is essential, as these stars exhibit a high molecular concentration in the spectral region λ = 1 to 5μm, producing a pseudo-continuum strongly dominated by molecular features, such as those of H2O and FeH. Once the line list was completed, we focused on the analysis of spectra of Barnard’s Star, determining its effective temperature, surface gravity, metallicity, and chemical abundances using the BACCHUS code, and subsequently employing this star to validate the line list developed in this work. Observatorio Nacional Dissertação 2026-03-20T00:00:00Z http://localhost:8080/tede/handle/tede/221 “ANÁLISE PRELIMINAR DA CLASSIFICAÇÃO TAXONÔMICA DE PEQUENOS CORPOS DO SISTEMA SOLAR A PARTIR DE DADOS DA CAMPANHA FOTOMÉTRICA J-PLUS” Cilio Marques Santos, Cilio Marques Santos Jorge Marcio Ferreira Carvano , Jorge Marcio Ferreira Carvano We classified 170 asteroids based on reflectances obtained in the J-PLUS photometric campaign. The data used were corrected using a genetic algorithm that aimed to correct noise due to rotation. We used Principal Component Analysis and K-MEANS cluster analysis as classification methods. Our classification resulted in twelve groups, with five spectrally close to class S, with a band at 1.0 microns associated with the possible presence of silicates; three to class C, with no absorption characteristics; two to classes V and Q with a very pronounced band to the right of 0.77 microns; one to class K or L; and one to class Ch, with a pronounced band at 0.7 microns, associated with hydration. Since the definition of nomenclature was based on visual inspection comparing the Bus classes, we chose to define a scheme that indicates the two most likely classes. In terms of the heliocentric distribution, we did not find results that differ from previous works Observatorio Nacional Dissertação 2025-09-05T00:00:00Z http://localhost:8080/tede/handle/tede/213 “O ELO PERDIDO NA EVOLUÇÃO DE RÁDIO-GALÁXIAS: INVESTIGANDO EMISSÕES ESTENDIDAS EM BAIXA FREQUÊNCIA” Vinícius Sanches Moreira Lima, Vinícius Sanches Moreira Lima Alberto Rodríguez Ardila , Alberto Rodríguez Ardila Active galactic nuclei (AGNs) with jets are morphologically classified according to their evolutionary stage, with Gigahertz Peaked-Spectrum (GPS) and Compact SteepSpectrum (CSS) sources traditionally understood as representing the young and confined phase of jets. However, the paradigm of a linear evolution has been challenged by an abundance of compact sources and the discovery of objects featuring a young nucleus embedded within a structure related to extended and aged emission, indicating multiple episodes of activity (“restarted” jets). This work aims to re-evaluate a sample of 84 sources previously classified as GPS/CSS by leveraging the unparalleled sensitivity of the LOFAR Two-metre Sky Survey (LoTSS) at 144 MHz to detect extended, low-surface-brightness emission undetectable in surveys above 1 GHz. We combined multi-frequency data (from 144 MHz to 4.85 GHz) to perform a comparative morphological analysis and construct Spectral Energy Distributions (SEDs). Our results show that 9 sources (17.3%) display clear morphological evidence of extended emission, being classified as restarted. Another 9 sources (17.3%) are classified as restarted jet candidates, and 28 (53.8%) remain compact. Spectral analysis reveals a diversity of classes (GPS, CSS, HFP, and spectra without peaks or flattened at low frequencies), with a tendency for restarted sources to have steeper (CSS-like) spectra. We conclude that a significant fraction of compact sources are, in fact, restarted jets, suggesting that jet activity is a cyclic and intermittent process. This result has profound implications for evolutionary models of radio galaxies and for the understanding of feedback exerted by multiple episodes of activity Observatorio Nacional Dissertação 2025-10-08T00:00:00Z