  Hawking has predicted that the formation of a black hole by gravitational
collapse causes quantum particle creation and the spectrum of the particles is
almost thermal. This phenomenon is called the Hawking radiation. Recently, it
has been predicted that the particle creation may drastically change from the
Hawking radiation to a strong double burst if the gravitational collapse
suddenly stops just before the formation of the event horizon. By contrast with
the Hawking radiation, the burst may be so strong that it can be of
observational interest even for collapsing objects with astrophysical mass
scales. However, the burst phenomenon has been predicted through the studies of
idealized models in which a spherical hollow shell begins to collapse, but
stops shrinking and eventually settles down to a static "star". Therefore, one
might guess that it could be particular to the hollow shell model. In this
paper, we study the particle creation due to the gravitational collapse of a
spherical object whose interior is filled with matter. In this model, we obtain
similar results to those in the case of the hollow shell model. This implies
that the double burst is a robust property of particle creation by the sudden
braking of gravitational collapse.
