Analytic self-force calculations in the post-Newtonian regime: eccentric orbits on a Schwarzschild background

TL;DR

This paper develops a method for calculating first-order metric perturbations in a post-Newtonian framework for eccentric orbits around a Schwarzschild black hole, improving accuracy for high eccentricities and deriving new gauge-invariant quantities.

Contribution

It generalizes existing methods to eccentric orbits, derives explicit expressions for metric perturbations, and computes high-order post-Newtonian contributions to gauge-invariant quantities and the effective one body potential.

Findings

Derived retarded metric perturbation expressions for all mbda-modes.

Confirmed the Regge-Wheeler gauge metric perturbation is  continuous at the particle.

Computed 4PN contributions to ngle U ngle and the effective one body potential ap Qap.

Abstract

We present a method for solving the first-order field equations in a post-Newtonian (PN) expansion. Our calculations generalize work of Bini and Damour and subsequently Kavanagh et al., to consider eccentric orbits on a Schwarzschild background. We derive expressions for the retarded metric perturbation at the location of the particle for all $\ell$-modes. We find that, despite first appearances, the Regge-Wheeler gauge metric perturbation is $C^0$ at the particle for all $\ell$. As a first use of our solutions, we compute the gauge-invariant quantity $\langle U \rangle$ through 4PN while simultaneously expanding in eccentricity through $e^{10}$. By anticipating the $e\to 1$ singular behavior at each PN order, we greatly improve the accuracy of our results for large $e$. We use $\langle U \rangle$ to find 4PN contributions to the effective one body potential $\hat Q$ through $e^{10}$ and at linear order in the mass-ratio.