Scattering of tidally interacting bodies in post-Minkowskian gravity

TL;DR

This paper extends the post-Minkowskian framework to include tidal effects in binary systems, calculating tidal invariants and their impact on scattering angles without assuming small velocities.

Contribution

It introduces a method to incorporate tidal deformations into the post-Minkowskian approach for binary systems, including neutron stars.

Findings

Computed tidal invariants at first post-Minkowskian order

Derived contributions of tidal effects to the scattering angle

Extended effective field theory to include tidal interactions

Abstract

The post-Minkowskian approach to gravitationally interacting binary systems ({\it i.e.}, perturbation theory in $G$, without assuming small velocities) is extended to the computation of the dynamical effects induced by the tidal deformations of two extended bodies, such as neutron stars. Our derivation applies general properties of perturbed actions to the effective field theory description of tidally interacting bodies. We compute several tidal invariants (notably the integrated quadrupolar and octupolar actions) at the first post-Minkowskian order. The corresponding contributions to the scattering angle are derived.