Conservative Spin Magnitude Change in Orbital Evolution in General Relativity
Abstract
We show that physical scattering observables for compact spinning objects in general relativity can depend on additional degrees of freedom in the spin tensor beyond those described by the spin vector alone. The impulse, spin kick, and leading-order waveforms exhibit such a nontrivial dependence. A signal of this additional structure is the change in the magnitude of the spin vector under conservative Hamiltonian evolution, similar to our previous studies in electrodynamics. These additional degrees of freedom describe dynamical mass multipoles of compact objects and decouple for black holes. We also show that the conservative impulse, spin kick and change of the additional degrees of freedom are encoded in the eikonal phase.
Cite
@article{arxiv.2407.10928,
title = {Conservative Spin Magnitude Change in Orbital Evolution in General Relativity},
author = {Mark Alaverdian and Zvi Bern and Dimitrios Kosmopoulos and Andres Luna and Radu Roiban and Trevor Scheopner and Fei Teng},
journal= {arXiv preprint arXiv:2407.10928},
year = {2025}
}
Comments
8 pages, 1 figure, v2 minor corrections