Testing eccentric corrections to the radiation-reaction force in the test-mass limit of effective-one-body models

TL;DR

This paper evaluates an effective-one-body radiation-reaction force for eccentric orbits in Kerr spacetime, comparing analytical and numerical fluxes to assess accuracy and inform future eccentric waveform modeling.

Contribution

It tests and compares different PN truncations of the radiation-reaction force against numerical fluxes for eccentric orbits in Kerr background.

Findings

Fractional difference with numerical fluxes is less than 5%.

PN truncations show expected scaling in weak-field regime.

Results inform development of eccentric models for comparable-mass systems.

Abstract

In this work, we test an effective-one-body radiation-reaction force for eccentric planar orbits of a test mass in a Kerr background, which contains third-order post-Newtonian (PN) non-spinning and second-order PN spin contributions. We compare the analytical fluxes connected to two different resummations of this force, truncated at different PN orders in the eccentric sector, with the numerical fluxes computed through the use of frequency- and time-domain Teukolsky-equation codes. We find that the different PN truncations of the radiation-reaction force show the expected scaling in the weak gravitational-field regime, and we observe a fractional difference with the numerical fluxes that is $<5 \%$, for orbits characterized by eccentricity $0 \le e \le 0.7$, central black-hole spin $-0.99 M \le a \le 0.99 M$ and fixed orbital-averaged quantity $x=\langle M\Omega \rangle^{2/3} = 0.06$, corresponding to the mildly strong-field regime with semilatera recta $9 M<p<17 M$. Our analysis provides useful information for the development of spin-aligned eccentric models in the comparable-mass case.