Using the spinning, supersymmetric Worldline Quantum Field Theory formalism
we compute the momentum impulse and spin kick from a scattering of two spinning
black holes or neutron stars up to quadratic order in spin at third
post-Minkowskian (PM) order, including radiation-reaction effects and with
arbitrarily mis-aligned spin directions. Parts of these observables, both
conservative and radiative, are also inferred from lower-PM scattering data by
extending Bini and Damour’s linear response formula. By solving Hamilton’s
equations of motion we also use a conservative scattering angle to infer a
complete 3PM two-body Hamiltonian including finite-size corrections and
misaligned spin-spin interactions. Finally, we describe mappings to the bound
two-body dynamics for aligned spin vectors: including a numerical plot of the
binding energy for circular orbits compared with numerical relativity, analytic
confirmation of the NNLO PN binding energy and the energy loss over successive
orbits.
