Coincident morphological transitions in precessing black-hole binaries

We got back to spin morphologies, which is something we found almost 10 years ago (here!). That’s a neat (IMO at least) way to classify the dynamics of black hole binaries using the qualitative evolution of their spins. Once can have transitions between these mutually exclusive classes of solutions. Here we systematically look at all configurations where two transitions take place concurrently. While restrictive, but it turns out these configurations can all be computed analytically at 2PN. This short paper came out of Giulia Foroni’s BSc project, it’s a fun calculation!

D. Gerosa, G. Foroni, G. Fumagalli, E. Berti.
ICBS proceedings. arXiv:2508.19735 [gr-qc].