2 FAMILIES OF EXACT DISKS WITH A CENTRAL BLACK-HOLE

The gravitational field of a configuration formed by a static disk and a Schwarzschild black hole is analysed for two families of disks. The matter of the disks is made of counter-rotating particles with as man y particles rotating to one side as to the other, in such a way that t he net angular momentum is zero and the disk is static. The first fami ly consists of peculiar disks, in the sense that they are generated by two opposite dipoles. The particles of the disk have no pressure or c entrifugal support. However, when there is a central black hole, centr ifugal balance in the form of counter-rotation appears. The second fam ily is a one parameter family of self-similar disks which includes at one end a Newtonian disk, and at the other a topological defect of spa cetime. The presence of the black hole impresses more rotational veloc ity to the particles. These two families are of infinite extent. Some interesting physical effects are studied.