Currently most hypotheses about black holes are physically impossible and thus irrealistic.
Following hypotheses are conform to reality:
Black holes consist of bound neutrinos and therefore are called by New Physics/SURe neutrino stars. The mutual bondings of omnipresent neutrinos (currently called dark matter) occur at very low temperatures. The condensation reaction is identical to freezing.
Frozen neutrinos are called by New Physics neutrinium.
Supermassive neutrino stars were the first stars in universe.
Stellar neutrino stars are generated by reaction of neutronium (condensed neutrons) of neutron stars to neutrinium. The reaction releases neutrinos as radiation energy, which is the origin of the strong radiation of so called quasars.
Contrary to current hypothesis there is zero gravitation in and on surface of neutrino stars. There is a high concentration of omipresent neutrinos near surface but there is no concentration gradient. Gravitational force depends on concentration gradient of neutrinos. The gravitational force starts at a specific distance to Neutrino star and then rapidly increases. The low gravitational force is verified by extreme low orbital velocities of stars near center of galaxy.
This is the origin of the so called bulge of galaxies. The gallactic bulge is a hollow sphere around supermassive neutrino stars with a high density of all kind of celestial bodies.
Gravitation is fully described and explained by New Physics.
Neutrino stars absorb high energetic radiation (=radiated neutrinos) and emit low energetic neutrinos. Emitted low energetic neutrinos are bound to huge and strong gravitational fields.