Constraining unmodeled physics with compact binary mergers from GWTC-1

We present a flexible model to describe the effects of generic deviations of observed gravitational-wave signals from modeled waveforms in the LIGO and Virgo gravitational-wave detectors. With the detection of 11 gravitational-wave events from the GWTC-1 catalog, we are able to constrain possible deviations from our modeled waveforms. In this paper, we present our coherent spline model that describes the deviations, then choose to validate our model on an example phenomenological and astrophysically motivated departure in waveforms based on extreme spontaneous scalarization. We find that the model is capable of recovering the simulated deviations. By performing model comparisons, we observe that the spline model effectively describes the simulated departures better than a normal compact binary coalescence (CBC) model. We analyze the entire GWTC-1 catalog of events with our model and compare it to a normal CBC model, finding that there are no significant departures from the modeled template gravitational waveforms used.