Binary black holes in the heat of merger

Abstract: A black hole binary approaching merger undergoes changes in its inspiral rate as energy and angular momentum are lost from the orbits into the horizons. This effect strengthens as the black holes come closer. We use numerical relativity data to model this so-called tidal heating in the strong gravity regime. We present a frequency-domain approximant for nonspinning black hole binaries that accounts for tidal heating effects up to the merger frequency. The approximant includes horizon parameters that characterize the nature of the compact objects. By applying this model to a binary black hole baseline that incorporates tidal heating, one can construct a more accurate point-particle waveform, one that is devoid of finite-size effects of the component objects. We also discuss its ramifications in modeling binary neutron star systems.