Can slow roll inflation induce relevant helical magnetic fields

By R. Durrer, Lukas Hollenstein, R. K. Jain. 2010

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We study the generation of helical magnetic fields during single field inflation induced by an axial coupling of the electromagnetic field to the inflaton. During slow roll inflation, we find that such a coupling always leads to a blue spectrum with $B^2(k) \propto k$, as long as the theory is treated perturbatively. The magnetic energy density at the end of inflation is found to be typically too small to backreact on the background dynamics of the inflaton. We also show that a short deviation from slow roll does not result in strong modifications to the shape of the spectrum. We calculate the evolution of the correlation length and the field amplitude during the inverse cascade and viscous damping of the helical magnetic field in the radiation era after inflation. We conclude that except for low scale inflation with very strong coupling, the magnetic fields generated by such an axial coupling in single field slow roll inflation with perturbative coupling to the inflaton are too weak to provide the seeds for the observed fields in galaxies and clusters.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ba10ed2dc0d734c4c4689e529782268e45e90370

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Citations in the corpus

Adding helicity to inflationary magnetogenesis (2014, methodology): “Our analysis will therefore update the one of [12] as well as the subsequent one of [25].”
Magnetogenesis from axion inflation (2016, background): “The helical magnetic field generated during inflation by a pure Maxwell action and a coupling term Vinteraction = I(φ)FμνF̃ μν was studied in [46] and found to be insufficient for satisfying observational limits.”
A review of axion inflation in the era of Planck (2013, background): “This issue was further studied in [47], which reaches more pessimistic conclusions than [45], based on different assumptions on the inverse cascade post-inflationary evolution of the magnetic field.”
Cosmological Magnetic Fields: Their Generation, Evolution and Observation (2013, methodology): “Finally, if the field is helical, as suggested e.g. by Durrer et al (2011), helicity conservation forces it to evolve along the significantly flatter path, B ∼ λ−0.5.”
Gauge field production in supergravity inflation: Local non-Gaussianity and primordial black holes (2012, background): “The study of the phenomenological effects of such a coupling during inflation has received a lot of attention lately [27–33].”