Gravitational waves and dark matter with witten effect

We present an investigation of cosmological implications resulting from spontaneous dark SU(2)d symmetry breaking in conjunction with the Witten effect. Furthermore, we examine the mass of hidden monopoles generated by the phase transition, as well as the impact of axion-monopole interactions on the axion mass. Following spontaneous breaking of the PQ symmetry, axions emitted by cosmic strings or domain walls, as well as hidden monopoles generated during this transition, may collectively contribute to the observed dark matter relic density. Additionally, the stochastic gravitational wave background generated by sub-GeV phase transitions and by the decay of axionic domain walls formed during sub-ZeV phase transitions could account for the low-frequency gravitational wave signals detected by PTA experiments.