Generalized Carter constant for quadrupolar test bodies in Kerr spacetime

We establish the existence of a deformation of the usual Carter constant which is conserved along the motion in a fixed Kerr background of a spinning test body possessing the spin-induced quadrupole coupling of a black hole. The conservation holds perturbatively up to second order in the test body&#...

Full description

Bibliographic Details
Main Author: Geoffrey Compère, Adrien Druart, Justin Vines
Format: Article
Language:English
Published: SciPost 2023-12-01
Series:SciPost Physics
Online Access:https://scipost.org/SciPostPhys.15.6.226
Description
Summary:We establish the existence of a deformation of the usual Carter constant which is conserved along the motion in a fixed Kerr background of a spinning test body possessing the spin-induced quadrupole coupling of a black hole. The conservation holds perturbatively up to second order in the test body's spin. This constant of motion is obtained through the explicit resolution of the conservation constraint equations, employing covariant algebraic and differential relations amongst covariant building blocks of the Kerr background. For generic spin-induced quadrupole couplings, which describe compact objects such as neutron stars, we obtain a no-go result on the existence of such a conserved quantity.
ISSN:2542-4653