A Mass Ratio Limit for Primordial Black Holes

Abstract

We augment our scenario for the formation of astronomical objects from macroscopic superstrings by the assumption that the central matter keeps its identity in the fragmentation. From the condition that the angular momentum per mass squared of this matter should be less than the Kerr limit G/c, we obtain upper limits for the ratio of the mass of central black holes M(BH) to the mass M of the host object. This limit is M(BH)/M ≈ 0.001, and, expressed in observed quantities, approximately M(BH)/M ≈σ2/(v · c) where σ is the r.m.s. velocity, v the rotational velocity and c the velocity of light. The values M(BH) agree with the observed behaviour both in order of magnitude and in the variation with velocity dispersion. Show more