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Regularization of second-order scalar perturbation produced by a point-particle with a nonlinear coupling

Eran Rosenthal
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Abstract

Accurate calculation of the motion of a compact object in a background spacetime induced by a supermassive black hole is required for the future detection of such binary systems by the gravitational-wave detector LISA. Reaching the desired accuracy requires calculation of the second-order gravitational perturbations produced by the compact object. At the point particle limit the second-order gravitational perturbation equations turn out to have highly singular source terms, for which the standard retarded solutions diverge. Here we study a simplified scalar toy-model in which a point particle induces a nonlinear scalar field in a given curved spacetime. The corresponding second-order scalar perturbation equation in this model is found to have a similar singular source term, and therefore its standard retarded solutions diverge. We develop a regularization method for constructing well-defined causal solutions for this equation. Notably these solutions differ from the standard retarded solutions, which are ill-defined in this case.

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Eran Rosenthal. 2005-01-13. Regularization of second-order scalar perturbation produced by a point-particle with a nonlinear coupling. https://doi.org/10.1088/0264-9381%2F22%2F15%2F013

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