Radiative losses from unbound orbits at quadratic order in spin from multipolar-post-Minkowskian formalism
Phys. Rev. D 114, 044093 – Published 26 August, 2026
DOI: https://doi.org/10.1103/wljs-s2px
Abstract
We study the spinning two-body system in the aligned spin case for hyperboliclike motions computing all radiative losses [at the 2 post-Newtonian (PN) absolute accuracy and including spin-squared corrections] using the MPM formalism and generalizing previous results valid at linear order in spin [D. Bini et al., Spin-orbit contribution to radiative losses for spinning binaries with aligned spins, Phys. Rev. D 108, 064049 (2023)]. Leading PM order results are checked against existing literature, whereas higher-order PM results (within the 2PN accuracy) are new with this work. As a byproduct of our general results we analyze the spinning situation which supports radial fall (at 2PN and including spin-squared accuracy level contributions), showing that as soon as the PN accuracy increases deviations from radial fall appear necessarily.
