Cosmological Ohm's law and dynamics of non-minimal electromagnetism
arXiv:1208.6547 · doi:10.1088/1475-7516/2013/01/013
Abstract
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.
24 pages, 2 figures; matches version published in JCAP
References in corpus (20)
- Large Nongaussianity in Axion Inflation
- Lower limit on the strength and filling factor of extragalactic magnetic fields
- Generation of Large-Scale Magnetic Fields in Single-Field Inflation
- Magnetic fields from inflation?
- Relativistic cosmology and large-scale structure
- N-flationary magnetic fields
- Generalized Ohm's law for relativistic plasmas
- Magnetic Fields from QCD Phase Transitions
- Reconstructing the dark energy equation of state with varying couplings
- From Equivalence Principles to Cosmology: Cosmic Polarization Rotation, CMB Observation, Neutrino Number Asymmetry, Lorentz Invariance and CPT
- Can the observed large scale magnetic fields be seeded by helical primordial fields?
- Cosmological magnetic fields from nonlinear effects
- The Evolution of the Large-Scale Tail of Primordial Magnetic Fields
- Limits on Cosmological Birefringence from the Ultraviolet Polarization of Distant Radio Galaxies
- Primordial magnetic fields from second-order cosmological perturbations: Tight coupling approximation
- Time Evolution of the Large-Scale Tail of Nonhelical Primordial Magnetic Fields with Back-Reaction of the Turbulent Medium
- Electromagnetic Properties of the Early Universe
- The Parity Odd Universe, Dark Energy and QCD
- Magnetic Field Spectrum at Cosmological Recombination
- Cosmic Electromagnetic Fields due to Perturbations in the Gravitational Field