On-Shell Physics of Black Holes

TL;DR

This paper explores how on-shell scattering amplitudes can be used to compute classical observables relevant to black hole physics, including spin interactions, by deriving results in the post-Minkowskian expansion of general relativity.

Contribution

It introduces a method to derive classical black hole observables directly from on-shell amplitudes, including a worldsheet effective action for Kerr black hole spins.

Findings

Computed momentum impulse and radiated momentum for spinning particles.

Derived results for black hole interactions in the post-Minkowskian expansion.

Constructed an effective action for Kerr black hole spin interactions.

Abstract

On-shell scattering amplitudes have proven to be useful tools for tackling the two-body problem in general relativity. This thesis outlines how to compute relevant classical observables that are themselves on-shell, directly from amplitudes; examples considered are the momentum impulse, total radiated momentum, and angular impulse for spinning particles. As applications we derive results relevant for black hole physics, computing in the post-Minkowskian expansion of GR, and construct a worldsheet effective action for the leading spin interactions of Kerr black holes.