A new model proposes that dark matter could consist of 't Hooft-Polyakov magnetic monopoles, formed during a thermal phase transition in the early universe. Unlike stable elementary particles, the abundance of these monopoles is usually negligible. However, the study demonstrates that a relevant abundance is achievable if the lightest stable particle in the dark sector, a dark fermion, is sufficiently light for its abundance to be suppressed, yet heavy enough to satisfy constraints on dark radiation. This scenario opens a parameter window where magnetic monopoles could constitute dark matter.

In this model, the mass of the magnetic monopoles is estimated to be approximately 10^8 GeV or larger, depending on the characteristics of the phase transition that generated them. This high mass places these dark matter candidates beyond the reach of current conventional detection experiments. Nevertheless, the model necessarily predicts the existence of dark radiation, with a ΔN_eff value (the effective contribution to the number of neutrino degrees of freedom) close to current cosmological observational bounds.

Furthermore, if the dark phase transition was strongly first-order, the model predicts a gravitational wave spectrum that lies in a region potentially accessible to future interferometers. This offers a prospective avenue for the indirect detection of these monopoles through their cosmological imprints, opening new perspectives for the search for dark matter beyond elementary particles and current direct detection methods.