| MadSci Network: Astronomy |
How do astronomers know that the particles associated with Hawking radiation actually exist as no one has ever seen or recorded any appearance of them?
You are correct. At this point the evaporation of Black Holes is theoretical. No Black Hole has yet been detected as evaporating. However, Hawking radiation and the existence of virtual particles is another effect of the uncertainty principle that allows for the quantum tunneling of particles through energy barriers. The quantum tunneling effect allows nuclear reactions to occur in stars. The point is that Hawking radiation is a natural consequence of particle pair production very close to the event horizon of a Black Hole, and we have lots of other evidence for the theoretical basis for this pair production. Of course, there is still no direct evidence, and there probably won't be for quite a while.
Reference: The Cosmic Perspective by J. Bennett, M. Donahue, N. Schneider, M. Voit, 1998, p, 463ff
Try the links in the MadSci Library for more information on Astronomy.