Abstract:
We present new bounds on the cosmic abundance of magnetic monopoles based
on the survival of primordial magnetic fields during the reheating and radiation-dominated
epochs. The new bounds can be stronger than the conventional Parker bound from galactic magnetic fields, as well as bounds from direct searches. We also apply our bounds to monopoles produced by the primordial magnetic fields themselves through the Schwinger effect, and derive additional conditions for the survival of the primordial fields.
