I'm trying to understand the behavior of photons between the photon sphere and the event horizon. Here is what I think I understand so far :

  • the radius of the PS is 1.5 times the Schwarzschild radius
  • photons that "fall into" the photon sphere will not make it out
  • theoretically speaking, photons could leave the PS if they were shot straight away from the singularity while outside the EH, like, for instance, if an astronaut falling into a black hole past the PS but before reaching the EH was to point a laser away from the singularity.

Now, I've been thinking, high energy particles falling into a black hole could collide in the PS, emitting sub-particles and photons, some of which could be ejected out of the photon sphere.

First of all, I'd like to know if I've gotten something wrong. I also want to know if that effect would become more significant for a spinning BH with the accretion disk spinning around the same axis, since my understanding is that it would bring the accretion disk closer to the PS, and maybe increase how often those collisions would happen perhaps ? Finally, how much energy would the photons released from the collisions have ?

Thank you for your time

  • $\begingroup$ Welcome to Physics SE! You should make your question clear and precise so people can answer it better - good question by the way, I'm not sure of the answer $\endgroup$
    – Max
    Oct 30, 2021 at 21:59


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