Intergalactic Magnetogenesis at Cosmic Dawn by Photoionization

Understand

We present a detailed analysis of an astrophysical mechanism that generates cosmological magnetic fields during the Epoch of Reionization.

• It is based on the photoionization of the Intergalactic Medium by the first sources formed in the Universe.
• First the induction equation is derived, then the characteristic length and time scales of the mechanism are identified, and finally numerical applications are carried out for first stars, primordial galaxies and distant powerful quasars.
• In these simple examples, the strength of the generated magnetic fields varies between the order of $10^{-23}$ G on hundreds of kiloparsecs to $10^{-19}$ G on hundreds of parsecs in the neutral Intergalactic Medium between the Str\"omgren spheres of the sources.