Abstract
A viable class of magnetogenesis models can be constructed by coupling the kinetic term of the hypercharge to a spectator field whose dynamics does not affect the inflationary evolution. The magnetic power spectrum is explicitly related to the power spectrum of (adiabatic) curvature inhomogeneities when the quasi-de Sitter stage of expansion is driven by a single scalar degree of freedom. Depending upon the value of the slow-roll parameters, the amplitude of smoothed magnetic fields over a (comoving) Mpc scale can be as large as 0.01–0.1 nG at the epoch of the gravitational collapse of the protogalaxy. The contributions of the magnetic fields to the Sachs–Wolfe plateau and to the temperature autocorrelations in the Doppler region compare favourably with the constraints imposed by galactic magnetogenesis. Stimulating lessons are drawn on the interplay between magnetogenesis models and their possible CMB signatures.
Highlights
A viable class of magnetogenesis models can be constructed by coupling the kinetic term of the hypercharge to a spectator field whose dynamics does not affect the inflationary evolution
The latest analyses of the AUGER experiment demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 × 1019 eV and the positions of active galactic nuclei within 75 Mpc [5]
In the late sixties Harrison [7] suggested that cosmology and astrophysics are just two complementary aspects of the origin of large-scale magnetic fields
Summary
A viable class of magnetogenesis models can be constructed by coupling the kinetic term of the hypercharge to a spectator field whose dynamics does not affect the inflationary evolution. Solving Eq (12) during inflation and Eq (14) during radiation the boundary conditions (15) permit the estimate of the two point function of the hypermagnetic field operators for a generic time τ > τ1 where τ1 denotes the epoch of the sudden rise in the conductivity: 0|Bi(x, τ )Bj(y, τ )|0 =
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