A Model of Black Hole Evaporation and 4D Weyl Anomaly

We analyze the time evolution of a spherically-symmetric collapsing matter from the point of view that black holes evaporate by nature. We consider conformal matters and solve the semi-classical Einstein equation G(mu nu) = 8 pi G < T-mu nu > by using the four-dimensional Weyl anomaly with a large c coefficient. Here, < T-mu nu > contains the contribution from both the collapsing matter and Hawking radiation. The solution indicates that the collapsing matter forms a dense object and evaporates without horizon or singularity, and it has a surface, but looks like an ordinary black hole from the outside. Any object we recognize as a black hole should be such an object.