Relic gravitational waves from the chiral magnetic effect

Understand

Relic gravitational waves (GWs) can be produced by primordial magnetic fields.

• However, not much is known about the resulting GW amplitudes and their dependence on the details of the generation mechanism.
• Here we treat magnetic field generation through the chiral magnetic effect (CME) as a generic mechanism and explore its dependence on the speed of generation (the product of magnetic diffusivity and characteristic wavenumber) and the speed characterizing the maximum magnetic field strength expected from the CME.
• When the latter exceeds the former (regime I), the regime applicable to the early universe, we obtain an inverse cascade with moderate GW energy that scales with the third power of the magnetic energy.