Primordial magnetogenesis from a supercooled dynamical electroweak phase transition

Observations of $γ$-ray from blazars suggest the presence of magnetic fields in the intergalactic medium, which may require a primordial origin. Intense enough primordial magnetic fields can arise from theories of dynamical electroweak symmetry breaking during the big bang, where supercooling is ended by a strongly first order phase transition. We consider theories involving new scalars and possibly vectors, including thermal particle dark matter candidates. Intense enough magnetic fields can arise if the reheating temperature after the phase transition is below a few TeV. The same dynamics also leaves testable primordial gravitational waves and possibly primordial black holes.