Dark matter may reveal the origin of primordial magnetic fields

Magnetic fields

Magnetic fields, which are present on a colossal scale across the universe, continue to intrigue and puzzle scientists. One prevailing theory is that these magnetic fields are not a later cosmic development, but rather they were formed near the universe's inception.

In this study, researchers propose a novel approach to probing ancient magnetic fields. They suggest that if the fields are indeed primordial, they could lead to an increase in dark matter density perturbations on smaller scales, resulting in the formation of mini-halos of dark matter.

The detection of these mini-halos would be a significant indicator of the primordial nature of magnetic fields, shedding light on the universe's unseen components and illuminating aspects of the visible cosmos.

Prevailing hypothesis

Lead author Pranjal Ralegankar, an astrophysicist at SISSA, explains that magnetic fields are ubiquitous in the cosmos. A prevailing hypothesis is that the observed magnetic fields might have been produced in the early stages of the universe. However, this proposition lacks explanation in the standard model of physics.

To address this, the researchers propose a method to detect 'primordial' magnetic fields. Their approach is based on examining the influence of magnetic fields on dark matter. By exploring how primordial magnetic fields could amplify the density perturbations of electrons and protons in the early universe, they found that the result is the suppression of small-scale fluctuations and the formation of mini-halos of dark matter.

The study's findings suggest that the abundance of mini-halos is determined by the strength of primordial magnetic fields in the early universe, reinforcing the hypothesis that these fields formed very early, even within 1 second after the Big Bang.

Broader implications

This study represents a significant step forward in our understanding of the universe's earliest moments. It not only offers a new perspective on the origin of magnetic fields but also highlights the intricate interplay between visible and invisible cosmic components, opening new avenues for exploring the vast and mysterious expanse of our universe.

The research, published in the journal Physical Review Letters, showcases the potential of dark matter to reveal insights into the primordial magnetic fields that have intrigued scientists for years.