Cosmological magnetic field measurements

by Andrii Neronov (Universite de Paris & University of Geneva)

Tuesday 1 Dec 2020, 15:00 → 16:00 Europe/Stockholm

https://stockholmuniversity.zoom.us/j/940229961

https://ui.adsabs.harvard.edu/abs/2020arXiv200914174N/abstract

NANOGrav collaboration has recently reported evidence for existence of stochastic gravitational wave background in the 1-100 nHz frequency range. We argue that such background could have been produced by magneto-hydrodynamic (MHD) turbulence at the first-order cosmological QCD phase transition. NANOGrav measurements suggest the magnetic field parameters: the comoving field strength close to microGauss and the correlation length close to 10% of the Hubble radius at the QCD phase transition epoch. We notice that turbulent decay of non-helical magnetic field with such parameters leads to the sufficiently strong magnetic field at recombination epoch which has been previously proposed as a solution to the Hubble tension problem. We show that the MHD turbulence model of the NANOGrav signal can be tested via measurement of the relic magnetic field in the voids of the Large Scale Structure with gamma-ray telescopes like CTA.

NANOGRAV_neronov_01-12-20.pdf

Neronov_1-12-2020.mp4