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The existence of large-scale magnetic fields permeating galaxies, clusters of galaxies and cosmic voids can be explained by the production of magnetic field “seeds” in the Early Universe. One possibility is that magnetogenesis takes place in a system composed by axions, dark gauge fields and standard photons, whose interactions require a numerical approach to be properly resolved.
We study the production of primordial magnetic fields performing lattice simulations and assuming that photons couple with axion-like particles and dark photons. For pre-inflationary axions, the axion-gauge interactions lead to a transfer of axion energy to the gauge sector, allowing for the resonant production of dark electromagnetic fields, while the high conductivity of the primordial plasma damps the photon oscillations and hence the growth of standard electromagnetic fields. However, initial inhomogeneities of the axion field can change substantially the gauge field production with respect to the homogeneous axion field in the pre-inflationary scenario, boosting or suppressing (depending on the axion parameters and couplings) the magnetogenesis mechanism. It is found that when the axion mass is far lighter than the QCD axion model and the initial axion field is inhomogeneous, weak but cosmologically relevant standard magnetic fields can be generated on scales of the order of 0.1 kp.
Filippo Anzuini obtained his Bachelor and Master degrees at La Sapienza University in Rome, Italy. He started a PhD in 2018 at the University of Melbourne working with Professor Andrew Melatos. During his PhD research he studied the equation of state of dense matter, the magneto-thermal evolution of neutron stars and the phenomenology of Beyond Standard Model particles in compact objects. In 2022 Filippo joined Monash University as a Research Fellow, and he is currently a Postdoctoral Research Fellow at the University of Melbourne. His current research focuses on the phenomenology of dark matter candidates in compact objects and in the primordial Universe.