Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11799
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Item Stability of closed timelike curves in the Gödel universe(General Relativity and Gravitation, 2007-06-16) Rosa, Valéria M.; Letelier, Patricio S.We study, in some detail, the linear stability of closed timelike curves in the Gödel universe. We show that these curves are stable. We present a simple extension (deformation) of the Gödel metric that contains a class of closed timelike curves similar to the ones associated to the original metric. This extension correspond to the addition of matter whose energy-momentum tensor is analyzed. We find the conditions to have matter that satisfies the usual energy conditions. We study the stability of closed timelike curves in the presence of usual matter as well as in the presence of exotic matter (matter that does satisfy the above mentioned conditions). We find that the closed timelike curves in the Gödel universe with or without the inclusion of regular or exotic matter are stable under linear perturbations. We also find a sort of structural stability.Item Stability of closed timelike geodesics(Physics Letters A, 2007-10-15) Rosa, V. M.; Letelier, P. S.The existence and stability under linear perturbations of closed timelike geodesics (CTG) in Bonnor–Ward spacetime is studied in some detail. Regions where the CTG exist and are linearly stable are exhibited.Item Spinning strings, black holes and stable closed timelike geodesics(International Journal of Theoretical Physics, 2009-12-01) Rosa, Valéria M.; Letelier, Patricio S.The existence and stability under linear perturbation of closed timelike curves in the spacetime associated to Schwarzschild black hole pierced by a spinning string are studied. Due to the superposition of the black hole, we find that the spinning string spacetime is deformed in such a way to allow the existence of closed timelike geodesics.