- #36
Chalnoth
Science Advisor
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Well, matter always travels at lower than the speed of light, so clearly orbits for matter must be beyond the photon sphere. The photon sphere is, after all, just the orbit of matter in the high-energy limit, and it corresponds to unstable orbits. Any lower-energy orbit will be necessarily further away.ClamShell said:Why is that? Are you in fact referring to the unstable orbits that
slow(and stop) BH spin? I like the unstable orbits better than the
stable orbits if we are still referring to non-rotating BH's. Unstable
orbits carry away the energy that is spinning a BH...another reason
for non-rotating BH's to become more common. That stable orbits
for matter are further out than the photon sphere is not clear to me.
As for slowing down the BH spin, well, I wasn't referring to that issue at all. It was my understanding that the primary slowdown of BH spin comes from the generation of relativistic jets due to matter entering the ergosphere and being expelled out the poles.