Exploring Magnetic Fields in a Merging Galaxy: Comparing Polarization and Velocity Gradient in the Centaurus Galaxy

Abstract In this study, we apply the velocity gradient technique to the merging Centaurus galaxy. We compare gradient maps derived from the PHANGS-Atacama Large Millimeter/submillimeter Array 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 antialignment, consistent with previous reports that gradients tend to rotate 90° 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. This proves the general utility of velocity gradients for mapping magnetic fields in astrophysical objects with complex dynamics.