Magnetic fields permeate the Universe from cosmological to molecular cloud scales, but neither their origin nor the mechanism of how they grow in amplitude is pinned down. We have used DiRAC to make headway on this on two fronts. Firstly in Martin-Alvarez et al. 2018, MNRAS, 479,3348 we sought to understand whether hierarchical galaxy growth could amplify extremely weak (~ 10^-19 Gauss) primordial magnetic fields to micro-Gauss levels in present day galaxies. For this purpose, we ran a suite of constrained transport magnetohydrodynamical adaptive mesh refinement cosmological zoom simulations with different stellar feedback prescriptions. We found that cosmological accretion at high redshift excited a galactic turbulent dynamo, which amplified the magnetic field even in the absence of stellar feedback. Our convergence tests are the first in the literature to demonstrate the capture of the elusive turbulent dynamo in cosmological simulations of galaxies.

Secondly, in Katz et al. 2019, MNRAS, 484, 2620, we presented an algorithm to trace magnetic fields produced by different sources, ranging from primordial fields generated for example by inflation to magnetic fields injected by supernovae and black holes. The figure above displays the magnetic energy density, color-coded by origin (green corresponds to primordial magnetic fields, red denotes fields injected by supernovae, and blue indicates the interaction of the two) in one of our simulation outputs of a 150 kpc on a side cosmological volume at redshift 4. With this algorithm, we will be able to methodically explore the contributions of different sources to the magnetization of the Universe.