Circular polarization of gravitational waves from the early-universe turbulent sources

Abstract: I will present direct numerical simulations to compute the net circular polarization of gravitational waves from helical (chiral) turbulent sources in the early universe for a variety of initial conditions. I will discuss the resulting gravitational wave signal assuming different turbulence genesis such as magnetically or kinetically dominant cases. Under realistic physical conditions in the early universe we have computed numerically for the first time the total (integrated over all wavenumbers) polarization degree of the gravitational waves and its spectral distribution. Our major finding consists of the spectral polarization degree that strongly depends on the initial conditions. The peak of the spectral polarization degree occurs (in the wavenumber space) at twice the typical wavenumber of the source, as expected, and for the fully helical decaying turbulence, reaches its maximum (100\%) only at the peak. In addition, we have determined the temporal evolution of the turbulent sources as well as the resulting gravitational waves, showing that the dominant contribution to the spectral energy density happens shortly after the source activation and through artificially prolonged (slow decay) turbulence the increase of the gravitational wave amplitude at low frequencies can be achieved. Finally, I will address the detection prospects for the net polarization arguing that its detection contains clean information (including the generation mechanisms, time, and strength) about the sources of possible parity violations in the early universe.

cosmology and nongalactic astrophysicsother condensed matterquantum gasesstrongly correlated electronssuperconductivitygeneral relativity and quantum cosmologyHEP - theory

Audience: researchers in the topic

Carnegie Mellon theoretical physics