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In this work, we discuss the determination of the distance to the Large Magellanic Cloud (LMC) using the Leavitt Law, utilizing the public catalog of Classical Cepheid Variable stars from the observational project OGLE-IV (The Optical Gravitational Lensing Experiment Collection of Variable Stars), consisting of 4709 stars in the Large Magellanic Cloud. To determine the pulsation period of Cepheid Variable stars, we employ the computational algorithm \textit{Lomb-Scargle periodogram} modified for our data. Additionally, with the calculation of the period, we can derive a period-luminosity relation for Cepheid Variables in the Large Magellanic Cloud and, using an independent calibration distance, deduce their distance moduli. We also discuss some general theoretical concepts of the physical mechanism behind the oscillation of variable stars., Comment: in Portuguese language

This review presents an introduction to Quantum Cosmology, including the mathematical methods essential to the canonical approach, some of the existing conceptual problems and the connection of the models to possible observables., Comment: 11 pages, in Portuguese, 3 figures, version accepted for publication in Cadernos de Astronomia

Galaxy clusters are important cosmological probes since their abundance and spatial distribution are directly linked to structure formation on large scales. The principal uncertainty source on the cosmological parameter constraints concerns the cluster mass estimation from mass proxies. In addition, future surveys will provide a large amount of data, requiring an improvement in the accuracy of other elements used in the construction of cluster likelihoods. Therefore, accurate modeling of the mass-observable relations and reducing the effect of different systematic errors are fundamental steps for the success of cluster cosmology. In this work, we briefly review the abundance of galaxy clusters and discuss many sources of uncertainty. Os aglomerados de gal\'axias s\~ao importantes sondas cosmol\'ogicas, j\'a que a abund\^ancia e a distribui\c{c}\~ao espacial desses objetos est\~ao diretamente ligadas \`a forma\c{c}\~ao de estruturas em grandes escalas. A maior fonte de incerteza nas restri\c{c}\~oes de par\^ametros cosmol\'ogicos \'e origin\'aria das estimativas das massas dos aglomerados a partir da rela\c{c}\~ao massa-observ\'avel. Al\'em disso, os pr\'oximos grandes levantamentos fornecer\~ao uma grande quantidade de dados, requerendo uma melhoria na precis\~ao de outros elementos utilizados na constru\c{c}\~ao das verossimilhan\c{c}as de aglomerados. Portanto, uma modelagem precisa da rela\c{c}\~ao massa-observ\'avel e diminuir o efeito dos diferentes erros sistem\'aticos s\~ao passos fundamentais para o sucesso da cosmologia com aglomerados. Neste trabalho, fazemos uma breve revis\~ao da abund\^ancia de aglomerados de gal\'axias, e discuss\~ao de diferentes fontes de incerteza., Comment: 9 pages, text in Portuguese. Proceeding do evento As Astrocientistas: I Encontro Brasileiro de Meninas e Mulheres da Astrof\'isica, Cosmologia e Gravita\c{c}\~ao. Realizado remotamente entre 08 e 11 de fevereiro de 2021. https://astrocientistas.wixsite.com/astrocientistas

We are experiencing a period of extreme intellectual effervescence in the area of cosmology. A huge volume of observational data in unprecedented quantity and quality and a more consistent theoretical framework propelled cosmology to an era of precision, turning the discipline into a cutting-edge area of contemporary science. Observations with type Ia Supernovae (SNe Ia), showed that the expanding Universe is accelerating, an unexplained fact in the traditional decelerated model. Identifying the cause of this acceleration is the most fundamental problem in the area. As in the scientific renaissance, the solution will guide the course of the discipline in the near future and the possible answers (whether dark energy, some extension of general relativity or a still unknown mechanism) should also leverage the development of physics. In this context, without giving up a pedagogical approach, we present an overview of both the main theoretical results and the most significant observational discoveries of cosmology in the last 100 years. The saga of cosmology will be presented in a trilogy. In this article (Part I), based on the articles by Einstein, de Sitter, Friedmann, Lema\^itre and Hubble, we will describe the period between the origins of cosmology and the discovery of Universal expansion (1929). In Part II, we will see the period from 1930 to 1997, closing with the old standard decelerated model. The Part III will be entirely devoted to the accelerated model of the universe, the cosmic paradigm of the XXI century., Comment: 18 pages, 10 figures. To appear in Revista Brasileira de Ensino de F\'isica (in Portuguese)

General Relativity is the modern theory of gravitation. It has replaced the newtonian theory in the description of the gravitational phenomena. In spite of the remarkable success of the General Relativity Theory, the newtonian gravitational theory is still largely employed, since General Relativity, in most of the cases, just makes very small corrections to the newtonian predictions. Moreover, the newtonian theory is much simpler, technically and conceptually, when compared to the relativistic theory. In this text, we discuss the possibility of extending the traditional newtonian theory in order to incorporate typical relativistic effects, but keeping the simplicity of the newtonian framework. We denominate these extensions neo-newtonian theories. These theories are discussed mainly in the contexts of cosmology and compact astrophysical objects., Comment: Latex file, 18 pages, 5 figures in eps format. To appear in Mens Agitat journal, proceedings of the Encontro de F\'isica da Amaz\^onia Caribenha, held in Boa Vista, Roraima, Brazil, from 28 to 31 october 2014. In portuguese