Extracting Spectral Index of Intergalactic Magnetic Field from Radio
  Polarizations
  We explain the large scale correlations in radio polarization in terms of the
correlations of galaxy cluster/supercluster magnetic field. Assuming that the
polarization correlations closely follow the spatial correlations of the
background magnetic field we recover the magnetic field spectral index as
-2.74$\pm$0.04.This remarkably agrees with cluster magnetic field spectral
index obtained in cosmological magneto-hydrodynamic simulations. We discuss
possible physical scenarios in which the observed polarization alignment is
plausible.
