标题： 关于Kerr-de Sitter时空上因果测地线的行为 显示英文标题

标题： On the behavior of causal geodesics on a Kerr-de Sitter spacetime

摘要： 我们分析了Kerr-de Sitter时空上因果测地线的行为，特别强调它们的完备性性质。 我们建立了一个初始值问题（IVP），其解有助于全面理解这些时空中因果测地线。 避开旋转轴的因果测地线是完备的，除了那些碰到环状曲率奇点的测地线，而遇到环状奇点的测地线必然是赤道上的。 我们还展示了穿过或位于旋转轴上的测地线的存在性。 后一类测地线的方程显示了环状奇点的排斥性质。 本工作的结果表明，就因果测地线的性质而言，Kerr-de Sitter时空的行为与Kerr时空族相似。 显示英文摘要

摘要： We analyze the behavior of causal geodesics on a Kerr-de Sitter spacetime with particular emphasis on their completeness property. We set up an initial value problem (IVP) whose solutions lead to a global understanding of causal geodesics on these spacetime. Causal geodesics that avoid the rotation axis are complete except the ones that hit the ring-like curvature singularity and those that encounter the ring singularity are necessary equatorial ones. We also show the existence of geodesics that cross or lie on the rotation axis. The equations governing the latter family show the repulsive nature of the ring singularity. The results of this work show, that as far as properties of causal geodesics are concerned, Kerr-de Sitter spacetimes behave in a similar manner as the family of Kerr spacetimes.