  A gravitational bound state, called a Macro Holeum, is created from a very
large number of microscopic black holes of primordial or a non-primordial
origin. All of them undergo orbital motion, under the action of gravity, around
their common center of mass. Four classes of Macro Holeum emerge: H, BH, HH and
LH. The latter is a massless bundle of gravitational energy moving at the speed
of light. The others are Dark Matter objects. BH emits Hawking radiation but
the others do not. The presently existing black holes are identified with BH.
All, except LH, emit gravitational radiation due to internal quantum
transitions. Simple analytic formulae are derived for the energy eigenvalues,
mass, radius, density and the frequency of the gravitational radiation emitted
by Macro Holeums in terms of just two parameters which can be determined from
the gravitational spectra. We predict that black holes have internal structure
and that they and other Macro Holeums, having masses in the range 57 solar
masses to 870 solar masses, would emit hydrogen-like gravitational radiation in
the LIGO frequency range in the form of band or line spectra with a
considerable overlapping of the bands. This will be superposed on a uniform
background radiation coming from Macro Holeums at large distances greater than
100 Mpc.
  04.60.-m, 04.60.Bc, 04.30.-w, 04.30.Tv, 95.35.+d, 95.36.+x
