ON THE DERIVATION OF HAWKING RADIATION ASSOCIATED WITH THE FORMATION OF A BLACK-HOLE

We show how in gravitational collapse the Hawking radiation at large times is precisely related to a scaling limit on the sphere where the star radius crosses the Schwarzschild radius (as long as the back reaction of the radiation on the metric is neglected). For a free quantum field it can be exactly evaluated and the result agrees with Hawking's prediction. For a realistic quantum field theory no evaluation based on general principles seems possible. The outcoming radiation depends on the field theoretical model. © 1990 Springer-Verlag.