Polarized Cosmological Gravitational Waves from Primordial Helical   Turbulence
  We show that helical turbulence produced during a first-order phase transition generates circularly polarized cosmological gravitational waves (GWs). The characteristic frequency of these GWs for an extreme case of the phase transition model is around $10^{-3}$ --- $10^{-2}$ Hz with an energy density parameter as high as $10^{-12}$ --- $10^{-11}$. The possibility of detection is briefly discussed. 
Tina Kahniashvili (1,2), Grigol Gogoberidze (2), Bharat Ratra (1);   ((1) Kansas State University (USA), (2) Center for Plas...