PVLAS Experiment: Some Astrophysical Consequences
  The birefringent effects of photon-pseudoscalar boson (Goldstone) particle mixing in intergalactic magnetic field are calculated for cosmological objects. We use the recent results of PVLAS collaboration that reported recently the observation of a rotation of the polarization plane of light propagating through a transverse static magnetic field. Such results which were interpretated as arising due to conversion of photon into pseudoscalar with coupling strength $g_{a\gamma}\sim 4\times 10^{-6} GeV^{-1}$ allows us to estimate the intergalactic magnetic field magnitude as $\sim 10^{-16} G$ based on Hatsemekers et al. observations of extreme-scale alignments of quasar polarization vectors. We have analyzed some additional results of astronomical observations that could be explained by axion interpretation of the PVLAS data: a sharp steepening of the QSO continuum short ward of $\simeq 1100$\AA, observed circular polarization of AGNs and QSOs, discrepancy between observed intrinsic polarization of stars in the Local Bubble and stellar spectral classification. The observed polarization of stars in the Local Bubble can't be explained by interstellar origin. 
Yu.N. Gnedin, M.Yu. Piotrovich, T.M. Natsvlishvili