Tidal deformation of dynamical horizons in binary black hole mergers and its imprint on gravitational radiation

Using NR simulations, this work tracks generalized source multipole moments of dynamical-horizon geometry through inspiral, merger, and ringdown. During inspiral the horizons steadily acquire multipoles that vanish for isolated holes, dominated by a quadrupole component, and these multipoles encode detailed binary dynamics. The dominant quadrupole moment is shown to correlate strongly with the gravitational field at future null infinity, implying a direct imprint on the emitted waves. After merger, multipoles of the common horizon inherit structure from the individual horizons and then decay as the remnant settles to equilibrium.

Phys. Rev. D 109, 044033 (2024)