On the magnetic fields in voids
  We study the possible magnetization of cosmic voids by void galaxies.
Recently, observations revealed isolated starforming galaxies within the voids.
Furthermore, a major fraction of a voids volume is expected to be filled with
magnetic fields of a minimum strength of about $10^{-15}$ G on Mpc scales. We
estimate the transport of magnetic energy by cosmic rays (CR) from the void
galaxies into the voids. We assume that CRs and winds are able to leave small
isolated void galaxies shortly after they assembled, and then propagate within
the voids. For a typical void, we estimate the magnetic field strength and
volume filling factor depending on its void galaxy population and possible
contributions of strong active galactic nuclei (AGN) which border the voids. We
argue that the lower limit on the void magnetic field can be recovered, if a
small fraction of the magnetic energy contained in the void galaxies or void
bordering AGNs is distributed within the voids.
