Gravitational Waves from Early Universe Turbulent Sources at the QCD Scale

by Emma Clarke (Carnegie Mellon University)

Wednesday 19 Jan 2022, 13:30 → 14:30 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

Hybrid talk: https://stockholmuniversity.zoom.us/j/530682073  
+ a room TBA, likely on floor 4 of Hus3 at the Albano campus

Gravitational waves (GWs) may be sourced by hydrodynamic and  hydromagnetic turbulent sources in the early universe. I will discuss  the results of numerical simulations of GWs from the quantum chromodynamic (QCD) scale  induced by various models of primordial turbulence and show that the  efficiency of GW production and the GW energy spectra depend strongly on  the nature of the turbulence. Additionally, I will revisit big bang nucleosynthesis (BBN) upper limits on the  relativistic energy density in the early universe to properly account  for the decaying nature of turbulent sources. This allows larger  estimates of the initial strength of primordial magnetic fields and/or turbulent motions in the early universe and thus a more  powerful source for resulting relic GW signals with more optimistic  prospects for detection. I will address the prospects of detecting these GW signals from the QCD  scale through pulsar timing arrays and astrometric missions. In  particular, I will discuss the  potential of explaining the recent NANOGrav evidence for a stochastic GW background with  turbulence at the QCD scale and the constraints this observation could  place on the properties of such turbulence.

Clarke_2022-Jan-19.mp4