# Quasi-circular inspirals and plunges from non-spinning effective-one-body Hamiltonians with gravitational self-force information

## TL;DR

This paper develops a new effective-one-body Hamiltonian incorporating gravitational self-force data, removing coordinate singularities at the light-ring, and improves modeling of small mass ratio binary inspirals with better agreement to numerical relativity.

## Contribution

It introduces a gauge choice for the EOB Hamiltonian that eliminates light-ring divergences and integrates self-force and post-Newtonian information for enhanced binary inspiral modeling.

## Key findings

- The new Hamiltonian is free of light-ring poles.
- EOB models with SMR-3PN info match numerical relativity well.
- Improved accuracy for small mass ratio inspirals.

## Abstract

The self-force program aims at accurately modeling relativistic two-body systems with a small mass ratio (SMR). In the context of the effective-one-body (EOB) framework, current results from this program can be used to determine the effective metric components at linear order in the mass ratio, resumming post-Newtonian (PN) dynamics around the test-particle limit in the process. It was shown in [Akcay et al., Phys. Rev. D 86 (2012)] that, in the original (standard) EOB gauge, the SMR contribution to the metric component $g^\text{eff}_{tt}$ exhibits a coordinate singularity at the light-ring (LR) radius. In this paper, we adopt a different gauge for the EOB dynamics and obtain a Hamiltonian that is free of poles at the LR, with complete circular-orbit information at linear order in the mass ratio and non-circular-orbit and higher-order-in-mass-ratio terms up to 3PN order. We confirm the absence of the LR-divergence in such an EOB Hamiltonian via plunging trajectories through the LR radius. Moreover, we compare the binding energies and inspiral waveforms of EOB models with SMR, PN and mixed SMR-3PN information on a quasi-circular inspiral against numerical-relativity predictions. We find good agreement between NR simulations and EOB models with SMR-3PN information for both equal and unequal mass ratios. In particular, when compared to EOB inspiral waveforms with only 3PN information, EOB Hamiltonians with SMR-3PN information improves the modeling of binary systems with small mass ratios $q \lesssim 1/3$, with a dephasing accumulated in $\sim$30 gravitational-wave (GW) cycles being of the order of few hundredths of a radian up to 4 GW cycles before merger.