p. 11: “Despite observed spin-orbit misalignments in … BH X-ray binaries… mass accretion and tidal interactions will tend to re-align the binary”. Hmmm. We argued earlier that mass accretion in HMXBs doesn’t change spins, and tides won’t act on the BH, so why should they realign it?
Proposal: "Despite observed spin-orbit misalignments in massive stellar binaries [refs], mass transfer and tidal interactions will tend to realign the binary. On the other hand, there is some evidence observational evidence of spin-orbit misalignment in BH X-ray binaries [refs]. This is consistent with the expectation that a supernova natal kick (if any) will change the orbital plane and misalign the binary; the supernova can also tilt the spin angle…”
From Ilya: