LIMITS ON BLACK-HOLE FORMATION FROM COSMIC-STRING LOOPS

In theories with cosmic strings, a small fraction of string loops may collapse to form black holes. In this paper, various constraints on su ch models involving black holes are considered. Hawking radiation from black holes, gamma and cosmic ray flux limits and constraints from th e possible formation of stable black hole remnants are reanalyzed. The constraints which emerge from these considerations are remarkably clo se to those derived from the normalization of the cosmic string model to the cosmic microwave background anisotropies. [S0556-2821(98)05904- 9].