- Published 2010

A formalism to deal with high-order perturbations of a general spherical background was developed in earlier work [D. Brizuela, J.M. Martı́n-Garcı́a, and G.A. Mena Marugán, Phys. Rev. D 74, 044039 (2006); D. Brizuela, J.M. Martı́n-Garcı́a, and G.A. Mena Marugán, Phys. Rev. D 76, 024004 (2007)]. In this paper, we apply it to the particular case of a perfect fluid background. We have expressed the perturbations of the energy-momentum tensor at any order in terms of the perturbed fluid’s pressure, density, and velocity. In general, these expressions are not linear and have sources depending on lower-order perturbations. For the second-order case we make the explicit decomposition of these sources in tensor spherical harmonics. Then, a general procedure is given to evolve the perturbative equations of motions of the perfect fluid for any value of the harmonic label. Finally, with the problem of a spherical collapsing star in mind, we discuss the high-order perturbative matching conditions across a timelike surface, in particular, the surface separating the perfect fluid interior from the exterior vacuum.

@inproceedings{Brizuela2010HighorderPO,
title={High-order perturbations of a spherical collapsing star},
author={David Brizuela and Jos{\'e} M. Martı́n-Garcı́a and Ulrich Sperhake and Kostas D. Kokkotas},
year={2010}
}