Neutral hydrogen and magnetic fields in M83 observed with the SKA Pathfinder KAT-7

TL;DR

This study uses KAT-7 observations to analyze the neutral hydrogen distribution, magnetic fields, and outer disk structure of galaxy M83, revealing insights into its interaction with the environment and magnetic field topology.

Contribution

First detailed HI and magnetic field study of M83 with KAT-7, extending the rotation curve and analyzing the galaxy's outer disk and magnetic field structure.

Findings

Neutral hydrogen extends to 50 kpc with a sharp edge.

Magnetic field topology similar to other star-forming galaxies.

Outer disk influenced by environmental interactions.

Abstract

We present new KAT-7 observations of the neutral hydrogen (HI) spectral line, and polarized radio continuum emission, in the grand design spiral M83. These observations provide a sensitive probe of the outer disk structure and kinematics, revealing a vast and massive neutral gas distribution that appears to be tightly coupled to the interaction of the galaxy with the environment. We present a new rotation curve extending out to a radius of 50 kpc. Based on our new HI dataset and comparison with multiwavelength data from the literature we consider the impact of mergers on the outer disk and discuss the evolution of M83. We also study the periphery of the HI distribution and reveal a sharp edge to the gaseous disk that is consistent with photoionization or ram pressure from the intergalactic medium (IGM). The radio continuum emission is not nearly as extended as the HI and is restricted to the main optical disk. Despite the relatively low angular resolution we are able to draw broad conclusions about the large-scale magnetic field topology. We show that the magnetic field of M83 is similar in form to other nearby star forming galaxies, and suggest that the disk-halo interface may host a large-scale regular magnetic field.