Constraints on Cosmic Magnetic Monopoles Imposed by the Galactic Magnetic Field

Abstract

Constraints on a hypothetical galactic halo of magnetic monopoles imposed by the galactic magnetic field are discussed. If the field is due to electric currents then a disk-stabilizing galactic monopole halo cannot exist unless the monopole mass $m_M\gtrsim {10}^{21}$ GeV, and then the monopole flux $F_M\lesssim 5\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$. However, if the galactic field is due to monopole charge-density fluctuations then a halo can exist provided $m_M\gtrsim {10}^{17}$ GeV and $F_M\lesssim 5\times {10}^{-11\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$.