This paper came out of some discussions from our “Gravitational-wave snowballs” workshop in Sexten (Italy). We were discussing the good old problem of separating black-hole binary formation channels with spin measurements. Usually one says “aligned=isolated”, “isotropic=dynamical”. But then, some binaries that formed dynamically should also be eccentric. What we then realized is that, for those eccentric binaries and only for those, spin measurements can actually tell which of the dynamical channel (because there are many…) is at play.
Jakob Stegmann, Davide Gerosa, Isobel Romero-Shaw, Giulia Fumagalli, Hiromichi Tagawa, Lorenz Zwick.
arXiv:2505.13589 [astro-ph.HE].