D0-brane description of the charged black hole

The charged black hole is considered from the viewpoint of D0-brane in the matrix theory. It can be obtained from the Kaluza-Klein mechanism by boosti ng the Schwarzschild black hole in a circle, which is the compactified one- dimensional space. In particular, it shows how the extremal limit is realiz ed by the Boltzmann gas of D0-brane. In the course of our discussion, the v irial theorem for the statistical average plays an important role.