Cosmological Ohm's law and dynamics of non-minimal electromagnetism

The origin of large-scale magnetic fields in cosmic structures and the intergalactic medium is still poorly understood. We explore the effects of non-minimal couplings of electromagnetism on the cosmological evolution of currents and magnetic fields. In this context, we revisit the mildly non-linear...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2013-01, Vol.2013 (1), p.i-23
Main Authors: Hollenstein, Lukas, Jain, Rajeev Kumar, Urban, Federico R
Format: Article
Language:English
Subjects:
Adiabatic flow
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COSMOLOGY
Couplings
ELECTRIC CURRENTS
ELECTROMAGNETISM
EVOLUTION
INTERGALACTIC SPACE
MAGNETIC FIELDS
Mathematical analysis
NONLINEAR PROBLEMS
Nonlinearity
OHM LAW
Ohm's Law
PLASMA
Plasma dynamics
RECOMBINATION
SCALAR FIELDS
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Summary:The origin of large-scale magnetic fields in cosmic structures and the intergalactic medium is still poorly understood. We explore the effects of non-minimal couplings of electromagnetism on the cosmological evolution of currents and magnetic fields. In this context, we revisit the mildly non-linear plasma dynamics around recombination that are known to generate weak magnetic fields. We use the covariant approach to obtain a fully general and non-linear evolution equation for the plasma currents and derive a generalised Ohm law valid on large scales as well as in the presence of non-minimal couplings to cosmological (pseudo)scalar fields. Due to the sizeable conductivity of the plasma and the stringent observational bounds on such couplings, we conclude that modifications of the standard (adiabatic) evolution of magnetic fields are severely limited in these scenarios. Even at scales well beyond a Mpc, any departure from flux freezing behaviour is inhibited.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2013/01/013