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Abstract

We investigate the impact of post-adiabatic (1PA) terms on parameter
estimation for extreme and intermediate mass-ratio inspirals using
state-of-the-art waveform models. Our analysis is the first to employ Bayesian
inference to assess systematic errors for 1PA waveforms. We find that
neglecting 1PA terms introduces significant biases for the (small) mass ratio
$\epsilon \gtrsim 10^{-5}$ for quasi circular orbits in Schwarzschild
spacetime, which can be mitigated with resummed 3PN expressions at 1PA order.
Moreover, we show that the secondary spin is strongly correlated with the other
intrinsic parameters, and it can not be constrained for $\epsilon \lesssim
10^{-5}$. Finally, we highlight the need for addressing eccentric waveform
systematics in the small-mass-ratio regime, as they yield stronger biases than
the circular limit in both intrinsic and extrinsic parameters.