Horizon radiation reaction forces

TL;DR

This paper uses Effective Field Theory to analyze horizon dissipation effects on binary black hole dynamics, providing leading-order corrections to scattering angles and equations of motion, with implications for other compact objects.

Contribution

It introduces a novel EFT framework to compute horizon dissipation effects on gravitational interactions of binary systems, including corrections to scattering and orbital dynamics.

Findings

Dissipative effects modify the scattering angle at leading PM order.

Finite size effects in binary black holes are characterized by PN corrections.

Methods are applicable to other compact objects like neutron stars.

Abstract

Using Effective Field Theory (EFT) methods, we compute the effects of horizon dissipation on the gravitational interactions of relativistic binary black hole systems. We assume that the dynamics is perturbative, i.e it admits an expansion in powers of Newton's constant (post-Minkowskian, or PM, approximation). As applications, we compute corrections to the scattering angle in a black hole collision due to dissipative effects to leading PM order, as well as the post-Newtonian (PN) corrections to the equations of motion of binary black holes in non-relativistic orbits, which represents the leading order finite size effect in the equations of motion. The methods developed here are also applicable to the case of more general compact objects, eg. neutron stars, where the magnitude of the dissipative effects depends on non-gravitational physics (e.g, the equation of state for nuclear matter).