A natural explanation of the Galactic Magnetic Fields from multistate Scalar Field Dark Matter

TL;DR

This paper proposes that large-scale galactic magnetic fields naturally emerge from a multistate scalar field dark matter model charged under a local symmetry, linking magnetic phenomena to the quantum structure of dark matter halos.

Contribution

It extends previous multistate scalar field dark matter models by analyzing the coupled dynamics with a gauge field, showing how magnetic fields arise without altering dark matter density profiles.

Findings

Magnetic fields' spatial structure matches scalar field states.

Dark matter density distribution remains unchanged by gauge field.

Large-scale magnetic fields are generated by excited scalar modes.

Abstract

In this article, we investigate the possibility that the large-scale magnetic fields observed in galaxies, of the order of microgauss, arise naturally from a complex Scalar Field Dark Matter (SFDM) halo charged under a local $U(1)$ symmetry. Extending our previous work, where multistate SFDM solutions were shown to form ``gravitational atoms'' capable of explaining the anisotropic distribution of satellite galaxies (VPOS), we analyze here the coupled dynamics of the scalar and a gauge field at the perturbative level. By solving the perturbed Klein-Gordon and gauge-field equations, we find the temporal evolution and show that the spatial structure of the induced electromagnetic fields is governed by the same spherical Bessel functions and spherical harmonics that characterize the ground and excited states of the multi-state SFDM halo. Remarkably, the presence of the gauge field does not modify the dark-matter density distribution, which preserves the multi-state configuration previously obtained. Our results demonstrate that a charged multi-state SFDM halo can generate coherent, large-scale magnetic fields whose morphology is determined by the excited modes of the scalar field, providing a unified framework in which both galactic magnetic fields and VPOS-like structures originate from the underlying quantum nature of dark matter.