Implications of a Primordial Magnetic Field for Magnetic Monopoles, Axions, and Dirac Neutrinos

Abstract

We explore some particle physics implications of the growing evidence for a helical primordial magnetic field (PMF). From the interactions of magnetic monopoles and the PMF, we derive an upper bound on the monopole number density, $n(t_0)<1\times 10^{-20}{\mathrm{cm}}^{-3}$, which is a "primordial" analog of the Parker bound for the survival of galactic magnetic fields. Our bound is weaker than existing constraints, but it is derived under independent assumptions. We also show how improved measurements of the PMF at different redshifts can lead to further constraints on magnetic monopoles. Axions interact with the PMF due to the $\phi \mathbf{E}\cdot \mathbf{B}$ interaction. Including the effects of the cosmological plasma, we find that the helicity of the PMF is a source for the axion field. Although the magnitude of the source is small for the PMF, it could potentially be of interest in astrophysical environments. Finally we apply constraints on the neutrino magnetic dipole moment that arise from requiring successful big bang nucleosynthesis in the presence of a PMF, and using the suggested strength $\sim 10^{-14}\mathrm{G}$ and coherence length $\sim 10\mathrm{Mpc}$ we find ${\mu }_{\nu }\lesssim 10^{-16}{\mu }_B$.

v2: 12 pages, 2 figures, added discussion of axion-photon resonant conversion and CMB constraints

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• Lower limit on the strength and filling factor of extragalactic magnetic fields
• Evolution of Primordial Magnetic Fields from Phase Transitions
• Adding helicity to inflationary magnetogenesis
• Gamma-ray induced cascades and magnetic fields in intergalactic medium
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Cited by in corpus (24)

• Baryogenesis from Decaying Magnetic Helicity
• Small-scale structure in vector dark matter
• Electromagnetic Luminosity of the Coalescence of Charged Black Hole Binaries
• Influence of the turbulent motion on the chiral magnetic effect in the early Universe
• Primordial magnetic field generation via primordial black hole disks
• Dipole Radiation and Beyond from Axion Stars in Electromagnetic Fields
• Monopole-Antimonopole Pair Production in Primordial Magnetic Fields
• Parker Bound and Monopole Pair Production from Primordial Magnetic Fields
• Evolution of axions in the presence of primordial magnetic fields
• Fundamental Implications of Intergalactic Magnetic Field Observations
• Magnetic dynamo caused by axions in neutron stars
• Parker Bounds on Monopoles with Arbitrary Charge from Galactic and Primordial Magnetic Fields
• Monopole acceleration in intergalactic magnetic fields
• Exact formulations of relativistic electrodynamics and magnetohydrodynamics with helically coupled scalar field
• Interaction of inhomogeneous axions with magnetic fields in the early universe
• On the cosmological abundance of magnetic monopoles
• Axion electrodynamics and magnetohydrodynamics
• Vacuum instability due to the creation of neutral Fermion with anomalous magnetic moment by magnetic-field inhomogeneities
• Magnetic fields in inhomogeneous axion stars
• Spin-Flavor Oscillations of Relic Neutrinos in Primordial Magnetic Field
• Impact of Helical Electromagnetic Fields on the Axion Window
• Low mode approximation in the axion magnetohydrodynamics
• Recasting Experimental Constraints on Relativistic Magnetic Monopoles
• Evolution of Mirror Axion Solitons