Abstract Our ability to infer the true source properties of colliding black holes from gravitational wave observations requires not only accurate waveform models but also their correct use. A key property when evaluating time-domain models is when to start the waveform: choosing a time that is too late can omit low-frequency power from higher order multipoles. By focusing on binary systems with total mass ≥200 M⊙, we show that current detectors are sensitive to this missing power and biased source properties can be obtained. We show that for systems with total mass ≲ 300 M⊙, mass ratio ≳ 0.33, and signal-to-noise ratio ρ ≳ 20, templates starting at 20 Hz recover biased source properties. As the total mass increases, and the component masses become more asymmetric, templates starting from 13 Hz recover biased properties. If the gravitational-wave signal is observed at signal-to-noise ratio ρ 20, time-domain models can start from 20 Hz as statistical uncertainties dominate.
Ursell et al. (2026) studied this question.