Magnetic fields in the Large Magellanic Cloud and their connection to the Magellanic System

ABSTRACT Studying the Magellanic System can help us understand the role that magnetic fields play in the evolution and structure of interacting low-mass galaxies. We have measured the Faraday rotation measure (RM) of 185 extra-galactic radio sources behind the Large Magellanic Cloud (LMC) to determine the structure of the magnetic field of the LMC. These observations were conducted with the CSIRO Australia Telescope Compact Array (ATCA) with a frequency range of 1.6–3.0 GHz. Our observations double the density of the grid of RMs for the LMC. With these new RM observations in conjunction with previous measurements, we find that the |RM| on the east side of the LMC is greater than the west. Using dispersion measure information from known LMC pulsars, we find that the magnitude of the coherent line-of-sight (LOS) magnetic field, $B_{||}$, is weakest to the north-west of the LMC, and the random LOS magnetic field is stronger in the east side. We find that $B_{||}$ traces neutral hydrogen arm-like structures within the LMC. Overall, the LMC does not appear to have a magnetic field like that of the Small Magellanic Cloud and Magellanic Bridge, indicating that the LMC is not directly part of the ‘pan-Magellanic’ magnetic field.