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P. P. Kronberg (U. Toronto), H. Lesch, U. Hopp (U. Munich)
We apply what has been recently learned from starburst - driven ``superwinds,'' dwarf galaxy surveys, and galaxy merging scenarios, to demonstate how a substantial fraction of the intergalactic medium can be permeated by magnetized outflow material from the ``volcanic early universe.''
Galactic wind outflow scenarios have been parameterized in model calculations that are embedded in different cosmological scenarios, in which the earliest galaxies are assumed to form around z=10. We show how subsequent, acausal diffusion of magnetized gas can propagate the fields over substantial intergalactic distances within a Hubble time.
We conclude that dwarf galaxies can effectively ``seed'' the intergalactic medium with magnetic fields, for a wide range of outflow, and galaxy density parameters. If the first galaxies form at or before z ~10, in a heirarchical merging scenario, a substantial fraction of the interglactic medium will be permeated with a magnetic field at the present epoch. This i.g. field seeding is largely acccomplished by z ~6. Galactic outflows after that epoch have little global effect.
Our scenario is consistent with growing evidence for substantial and relatively strong fields in and around galaxy systems, even at large redshifts. Our model of intergalactic field generation would also likely ``mask'' any magnetic field seeding due to processes in the very early, pre-recombination universe, i.e. before z=1500. It also does not require it.