The Magnetic Field Across the Molecular Warped Disk of Centaurus A

TL;DR

This study uses polarized emission observations to analyze the magnetic field structure in the molecular warped disk of Centaurus A, revealing a large-scale ordered field and turbulent components influenced by galaxy merger processes.

Contribution

It provides new observational evidence linking magnetic field configurations to galaxy mergers and turbulence in the molecular disk of Centaurus A.

Findings

Magnetic fields follow the warped molecular disk structure.

Large-scale axisymmetric spiral magnetic field model fits observations.

Presence of small-scale turbulent magnetic fields increasing with velocity dispersion.

Abstract

Magnetic fields are amplified as a consequence of galaxy formation and turbulence-driven dynamos. Galaxy mergers can potentially amplify the magnetic fields from their progenitors, making the magnetic fields dynamically important. However, the effect of mergers on magnetic fields is still poorly understood. We use thermal polarized emission observations to trace the magnetic fields in the molecular disk of the nearest radio active galaxy, Centaurus A, which is thought to be the remnant of a merger. Here, we detect that the magnetic field orientations in the plane of the sky are tightly following the $\sim3.0$ kpc-scale molecular warped disk. Our simple regular large-scale axisymmetric spiral magnetic field model can explain, to some extent, the averaged magnetic field orientations across the disk projected on the sky. Our observations also suggest the presence of small-scale turbulent fields, whose relative strength increases with velocity dispersion and column density. These results have strong implications for understanding the generation and role of magnetic fields in the formation of galaxies across cosmic time.