Navegando por Assunto "Buraco negro de Schwarzschild"

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Acesso aberto (Open Access)
Electric charge rotating around a black hole
(2005-12) CASTIÑEIRAS RODRÍGUEZ, Jorge; CRISPINO, Luís Carlos Bassalo; FIGUEIRA, Rodrigo Murta de Andrade; MATSAS, George Emanuel Avraam
We consider an electric charge rotating around a Schwarzschild black hole. We compute, using quantum field theory in curved spacetime at the tree level, the power emitted by the rotating charge minimally coupled to the Maxwell field. We also compute how much of the radiation emitted by the swirling charge is absorbed by the black hole.
Acesso aberto (Open Access)
Seção de choque de absorção de buracos negros de Schwarzschild e de buracos acústicos canônicos
(Universidade Federal do Pará, 2008-02-22) OLIVEIRA, Ednilton Santos de; CRISPINO, Luís Carlos Bassalo; http://lattes.cnpq.br/4033994493756291
In this dissertation we compute the absorption cross section of Schwarzschild black holes for the massless scalar and electromagnetic fields. We also compute the absorption cross section of canonical acoustic holes for sound waves. We use a numerical method to obtain the results in arbitrary frequencies. We also obtain analytic expressions for the low- and high-frequency absorption cross sections. The numerical results are in excellent agreement with the low- and high-frequency absorption cross section values obtained analytically. In the zero-frequency limit the absorption cross section tends to the event horizon area value for both the massless scalar field in Schwarzschild spacetime and the canonical acoustic hole cases. However, as the frequency increases, these two results become very different. This shows that, although the spacetime geometry does not influence the absorption cross section in the zero-frequency limit, it is important for arbitrary frequencies. We also see that massless scalar and electromagnetic absorption cross section values for the Schwarzschild black hole coincide for high enough frequencies and angular momenta. The spin of the scattered particle, in this case, although being very important for low frequencies, becomes less relevant to the absorption cross section value as the frequency and the angular momentum of the incident particle increase.