Tootfinder

Spin-orbit misalignment and residual eccentricity are evidence that neutron star-black hole mergers form through triple star evolution
Jakob Stegmann, Jakub Klencki
https://arxiv.org/abs/2506.09121

Spin-orbit misalignment and residual eccentricity are evidence that neutron star-black hole mergers form through triple star evolution
There is growing evidence that a substantial fraction of the neutron star-black holes (NSBHs) detected through gravitational waves merge with non-zero eccentricity or large BH spin-orbit misalignment. This is in tension with the leading formation scenarios to date. Residual eccentricity rules out formation through isolated binary star evolution, while NS natal kicks and the unequal masses of NSBHs inhibit efficient pairing in dense stellar environments. Here, we report that all observed propert…