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Updated: Jul 10, 2025

Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Cosmic-void observations reconciled with primordial magnetogenesis
David N Hosking1,2,3,4, Alexander A Schekochihin5,6
1Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK. dhosking@princeton.edu.
Abstract:
It has been suggested that the weak magnetic field hosted by the intergalactic medium in cosmic voids could be a relic from the early Universe. However, accepted models of turbulent magnetohydrodynamic decay predict that the present-day strength of fields originally generated at the electroweak phase transition (EWPT) without parity violation would be too low to explain the observed scattering of γ-rays from TeV blazars. Here, we propose that the decay is mediated by magnetic reconnection and conserves the mean square fluctuation level of magnetic helicity. We find that the relic fields would be stronger by several orders of magnitude under this theory than was indicated by previous treatments, which restores the consistency of the EWPT-relic hypothesis with the observational constraints. Moreover, efficient EWPT magnetogenesis would produce relics at the strength required to resolve the Hubble tension via magnetic effects at recombination and seed galaxy-cluster fields close to their present-day strength.
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