ASTROPHYSICAL BOUNDS ON GLOBAL MONOPOLES

The gravitational field of a global monopole, recently found by Barriola and Vilenkin, is used to constrain the number density of global monopoles present in the Universe today. Requiring that the mass density in such monopoles should not greatly exceed the critical density implies that there is at most one global monopole in the local group of galaxies. Equally stringent bounds are also derived which do not depend on cosmological assumptions, using the large tidal gravitational forces associated with such monopoles. © 1990 The American Physical Society.