Exploring magnetic fields in merging galaxy: combining polarization and velocity gradient in the Centaurus Galaxy

TL;DR

This paper demonstrates that velocity gradient techniques combined with polarization data effectively trace magnetic fields in the merging Centaurus galaxy, revealing strong alignment and anti-alignment regions related to galactic outflows.

Contribution

It introduces the application of the Velocity Gradient Technique to a merging galaxy and compares it with dust polarization, showing their strong correspondence in magnetic field tracing.

Findings

Strong correlation between gradient-based magnetic field directions and polarization data.

Identification of anti-aligned regions in jet/outflow areas.

Higher accuracy of magnetic field alignment in high signal-to-noise regions.

Abstract

In this study, we apply the Velocity Gradient Technique (VGT) to the merging Centaurus galaxy. We compare gradient maps derived from the PHANGS-ALMA survey using CO emission lines with magnetic field tracings from dust polarization data obtained via the HAWC+ instrument. Our analysis reveals a strong correspondence between the directions indicated by these two tracers across most of the galactic image. Specifically, we identify jet regions as areas of anti-alignment, consistent with previous reports that gradients tend to rotate 90 degrees in outflow regions. Statistically, we find that the alignment of magnetic fields, as revealed by polarization, is most accurate in regions with the highest signal-to-noise ratios. Our findings underscore the utility of velocity gradients as a valuable complementary tool for probing magnetic fields and dynamical processes in merging galaxies.