MG12 - Talk detail
 

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Abstract

Dixon's extended bodies in black hole spacetimes

The motion of extended bodies with structure up to the mass quadrupole moment as described by Dixon's theory is discussed in Schwarzschild and Kerr spacetimes. The full set of evolution equations is solved under the simplifying assumptions of constant frame components for both the spin and the quadrupole tensors and that the center of mass moves along an equatorial circular orbit, the total 4-momentum of the body being aligned with it. Measurable effects are also investigated.

Kerr spacetime with arbitrary mass quadrupole moment: geometric properties and particle motion

An exact solution of Einstein’s field equations in empty space found in 1991 by Quevedo and Mashhoon is analyzed in detail. The solution generalizes Kerr spacetime to include the case of matter with arbitrary mass quadrupole moment and is specified by three parameters, the mass M, the angular momentum per unit mass a and the mass quadrupole moment q. It reduces to the Kerr spacetime in the limiting case q = 0 and to the Erez-Rosen spacetime when the specific angular momentum a vanishes. The geometrical properties of such a solution are investigated. Causality violations, directional singularities and repulsive effects occur in the region close to the source. Geodesic motion and accelerated motion are studied on the equatorial plane which, due to the reflection symmetry property of the solution, turns out to be also a geodesic plane.

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