@PhDThesis{Brandão:2010:DeFeCo,
               author = "Brand{\~a}o, Cl{\'a}udio Soriano de Souza",
                title = "Desenvolvimento de uma ferramenta computacional para a 
                         investigac{\~a}o de teorias de gravitac{\~a}o via c{\'o}digos 
                         de {\'a}rvore",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2010",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2010-04-16",
             keywords = "c{\'o}digos de {\'a}rvore, teorias de gravita{\c{c}}{\~a}o, 
                         relatividade geral, gal{\'a}xias, din{\^a}mica gal{\'a}ctica, 
                         treecodes, theories of gravitation, general relativity, galaxies, 
                         galactic dynamics.",
             abstract = "No limite n{\~a}o relativ{\'{\i}}stico, a Relatividade Geral se 
                         reduz, como se sabe, {\`a} gravita{\c{c}}{\~a}o newtoniana. 
                         Teorias alternativas {\`a} da Relatividade Geral, contudo, 
                         n{\~a}o necessariamente t{\^e}m esta propriedade. Uma vez que a 
                         gravita{\c{c}}{\~a}o newtoniana {\'e} largamente usada para 
                         modelar com {\^e}xito as estruturas do Universo, tais como 
                         gal{\'a}xias e aglomerados de gal{\'a}xias, por exemplo, um modo 
                         de investigar e vincular teorias alternativas, no limite 
                         n{\~a}o-relativ{\'{\i}}stico, {\'e} aplic{\'a}-las a modelos 
                         de estruturas do Universo. Nesta Tese, investigamos potenciais 
                         gravitacionais do tipo Yukawa, previstos por teorias alternativas 
                         no limite n{\~a}o-relativ{\'{\i}}stico, usando 
                         simula{\c{c}}{\~o}es num{\'e}ricas de sistemas auto-gravitantes 
                         atrav{\'e}s da Din{\^a}mica Gal{\'a}ctica. Como uma primeira 
                         aplica{\c{c}}{\~a}o do c{\'o}digo modificado Gadget-2, 
                         simulamos a evolu{\c{c}}{\~a}o de gal{\'a}xias 
                         el{\'{\i}}pticas e em seguida, modelamos a evolu{\c{c}}{\~a}o 
                         de gal{\'a}xias espirais sob a mesma teoria. Estas 
                         simula{\c{c}}{\~o}es mostram que a din{\^a}mica gal{\'a}ctica 
                         pode ser usada para vincular os par{\^a}metros associados com as 
                         teorias de gravita{\c{c}}{\~a}o em estudo. Usando estas 
                         t{\'e}cnicas, tamb{\'e}m investigamos a hip{\'o}tese de 
                         Brownstein-Moffat, que sustenta a inexist{\^e}ncia de halos de 
                         mat{\'e}ria escura em gal{\'a}xias espirais, cujas curvas de 
                         rota{\c{c}}{\~a}o s{\~a}o explicadas por potenciais 
                         an{\^o}malos em grandes escalas, contra o cen{\'a}rio 
                         padr{\~a}o descrito por um disco imerso num halo de mat{\'e}ria 
                         escura sob o potencial newtoniano. ABSTRACT: In the weak field 
                         limit General Relativity reduces, as is well known, to the 
                         Newtonian gravitation. Alternative theories to the General 
                         Relativity, however, do not necessarily have this property. Since 
                         the Newtonian gravitation is largely used to model with success 
                         the structures of the universe, such as galaxies and clusters of 
                         galaxies, for example, a way to probe and constrain alternative 
                         theories, in the weak field limit, is to apply them to mo del the 
                         structures of the universe. In the present study we consider how 
                         to probe Yukawa-like Potentials, which comes from the weak field 
                         limit of some alternative theories, using Numerical Simulations, 
                         in particular, a well known N -body code Gadget-2 to probe 
                         alternative theories of gravitation through galactic dynamics. In 
                         particular, we modified this code to probe alternatives theories 
                         whose weak field limits have a Yukawa-like gravitational 
                         potential. As a first application of this modified Gadget-2 code 
                         we simulate the evolution of elliptical and spiral galaxies. These 
                         simulations show that galactic dynamics can be used to constrain 
                         the parameters associated with alternative theories of 
                         gravitation. We also investigate the Brownstein-Moffat's 
                         hypothesis that claims late-type galaxies systems have not halos 
                         and are ruled by anomalous potentials, against standard scenario 
                         described by disk embembed a dark matter halo under Newton's 
                         potential, using the tecquiniques described above.",
            committee = "Souza, Carlos Alexandre Wuensche de (presidente) and Ara{\'u}jo, 
                         Jos{\'e} Carlos Neves de (orientador) and Aguiar, Odylio Denys de 
                         and Souza, Ronaldo Eust{\'a}quio de and Ribeiro, Andr{\'e} 
                         Lu{\'{\i}}s Batista",
           copyholder = "SID/SCD",
         englishtitle = "A computational tool kit to the investigation of theories of 
                         gravitation using treecodes",
             language = "pt",
                pages = "145",
                  ibi = "8JMKD3MGP7W/377P2MH",
                  url = "http://urlib.net/ibi/8JMKD3MGP7W/377P2MH",
        urlaccessdate = "18 maio 2024"
}