Primordial magnetic fields from metric perturbations

Abstract

We study the amplification of electromagnetic vacuum fluctuations induced by the evolution of scalar metric perturbations at the end of inflation. Such perturbations break the conformal invariance of Maxwell equations in Friedmann-Robertson-Walker backgrounds and allow the growth of magnetic fields on super-Hubble scales. We relate the strength of the fields generated by this mechanism with the power spectrum of scalar perturbations and estimate the amplification on galactic scales for different values of the spectral index. Finally we discuss the possible effects of finite conductivity during reheating.

10 pages, 1 figure. Final version to appear in Phys. Rev. D

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• Restoring the sting to metric preheating
• Resonant Amplification of Gauge Fields in Expanding Universe
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• Generic estimates for magnetic fields generated during inflation including Dirac-Born-Infeld theories
• Superadiabatic-type magnetic amplification in conventional cosmology
• Generation of electromagnetic fields in string cosmology with a massive scalar field on the anti D-brane
• The interrelation between the generation of large-scale electric fields and that of large-scale magnetic fields during inflation
• Cosmological magnetic fields from inflation in extended electromagnetism
• Cosmological Magnetogenesis driven by Radiation Pressure
• Primordial magnetic fields and gravitational baryogenesis in nonlinear electrodynamics
• Self consistent estimates of magnetic fields from reheating
• Property of the spectrum of large-scale magnetic fields from inflation
• Resonant amplification of magnetic seed fields by gravitational waves in the early universe
• Generation of large-scale magnetic fields, non-Gaussianity, and primordial gravitational waves in inflationary cosmology
• Dark energy, non-minimal couplings and the origin of cosmic magnetic fields
• Evolution of primordial magnetic fields in mean-field approximation
• Generation of large-scale magnetic fields from inflation in teleparallelism
• Nonlinear electrodynamics and CMB polarization
• Diamagnetic field states in cosmological plasmas
• Large-scale magnetic fields from inflation due to a $CPT$-even Chern-Simons-like term with Kalb-Ramond and scalar fields
• Magnetic fields from cosmological bulk flows
• Photon quantization in cosmological spaces
• Minimal Magnetogenesis: The Role of Inflationary Perturbations and ALPs, and Its Gravitational Wave Signatures
• Constraining the primordial spectrum of metric perturbations from gravitino and moduli production
• Chiral gravitational waves from multi-phase magnetogenesis
• The Impact of Inhomogeneous Perturbations of the Inflaton on the Cosmological Primordial Magnetic Field