Constraint on magnetized galactic outflows from LOFAR rotation measure data

TL;DR

This study uses LOFAR Rotation Measure data to test galaxy outflow models, finding that current simulations overestimate magnetic field pollution in the intergalactic medium, supporting a cosmological origin of large-scale magnetic fields.

Contribution

It provides observational constraints on galaxy outflow models, indicating they are less influential than previously simulated, supporting a cosmological origin of intergalactic magnetic fields.

Findings

Illustris-TNG over-predicts residual Rotation Measure

Magnetized outflows less influential than models suggest

Supports cosmological origin of large-scale magnetic fields

Abstract

Outflows from galaxies, driven by active galactic nuclei and star formation activity, spread magnetic fields into the intergalactic medium. Importance of this process can be assessed using cosmological magneto-hydrodynamic numerical modelling of the baryonic feedback on the Large Scale Structure, like that of Illustris-TNG simulations. We use the Faraday Rotation Measure data of LOFAR Two-Meter Sky Survey (LOTSS) to test the Illustris-TNG baryonic feedback model. We show that the Illustris-TNG over-predicts the root-mean-square of the residual Rotation Measure in LOTSS. This suggests that the "pollution" of the intergalactic medium by the magnetized outflows from galaxies is less important than the estimate from the Illustris-TNG. This fact provides a support to the hypothesis that the volume-filling large scale magnetic fields found in the voids of the Large Scale Structure are likely of cosmological origin.