EVAPORATION OF A KERR BLACK-HOLE BY EMISSION OF SCALAR AND HIGHER SPIN PARTICLES - ART. NO. 044012

We study the evolution of an evaporating rotating black hole, describe d by the Kerr metric, which is emitting either solely massless scalar particles or a mixture of massless scalar and nonzero spin particles. Allowing the hole to radiate scalar particles increases the mass loss rate and decreases the angular momentum loss rate relative to a black hole which is radiating nonzero spin particles. The presence of scalar radiation can cause the evaporating hole to asymptotically approach a state which is described by a nonzero value of a=a/M. This is contra ry to the conventional view of black hole evaporation, wherein all bla ck holes spin down more rapidly than they lose mass. A hole emitting s olely scalar radiation will approach a final asymptotic state describe d by asimilar or equal to 0.555. A black hole that is emitting scalar particles and a canonical set of nonzero spin particles (3 species of neutrinos, a single photon species, and a single graviton species) wi ll asymptotically approach a nonzero value of a only if there are at least 32 massless scalar fields. We also calculate the lifetime of a p rimordial black hole that formed with a value of the rotation paramete r a,, the minimum initial mass of a primordial black hole that is seen today with a rotation parameter a,, and the entropy of a black hole t hat is emitting scalar or higher spin particles. [S0556-2821(98)05316- 8].