Observational identification of spin inversions in gravitational-wave data

Determine whether one-off spin flips, recurrent spin flip-flops, and quadrupole-induced spin inversions in compact binaries can be successfully identified in gravitational-wave observations.

Background

The paper studies spin inversions predicted by secular post-Newtonian dynamics, including unequal-mass one-off flips, comparable-mass recurrent flip-flops, and quadrupole-induced inversions. These dynamics alter the relative orientations of the component spins and the orbital angular momentum, but gravitational-wave detectors observe only the resulting strain rather than the underlying spin geometry directly.

The restricted waveform analysis demonstrates strong degeneracies between several spin-inverting injections and physically evolving no-inversion binaries. Consequently, the broader question of whether such geometric effects can be recognized in actual gravitational-wave data remains unresolved, especially beyond the restricted waveform model used in the paper.