Polarization of gravitational waves from helical MHD turbulent sources

Understand

We use direct numerical simulations of decaying primordial hydromagnetic turbulence with helicity to compute the resulting gravitational wave (GW) production and its degree of circular polarization.

• We find a clear dependence of the polarization of the resulting GWs on the fractional helicity of the turbulent source and we show that driven magnetic fields produce GWs more efficiently than magnetic fields that are initially present, leading to larger spectral amplitudes.
• The helicity does not have a huge impact on the maximum spectral amplitude in any of the two types of turbulence considered.
• However, the GW spectrum at wave numbers away from the peak becomes smaller for larger values of the magnetic fractional helicity.