Kavli Affiliate: R. Morris
| First 5 Authors: Dylan M. Paré, Cormac R. Purcell, Cornelia C. Lang, Mark R. Morris, James A. Green
| Summary:
The Radio Arc is a system of organized non-thermal filaments (NTFs) located
within the Galactic Center (GC) region of the Milky Way. Recent observations of
the Radio Arc NTFs revealed a magnetic field which alternates between being
parallel and rotated with respect to the orientation of the filaments. This
pattern is in stark contrast to the predominantly parallel magnetic field
orientations observed in other GC NTFs. To help elucidate the origin of this
pattern, we analyze spectro-polarimetric data of the Radio Arc NTFs using an
Australian Telescope Compact Array data set covering the continuous frequency
range from $sim$4 to 11 GHz at a spectral resolution of 2 MHz. We fit
depolarization models to the spectral polarization data to characterize Faraday
effects along the line-of-sight. We assess whether structures local to the
Radio Arc NTFs may contribute to the unusual magnetic field orientation.
External Faraday effects are identified as the most likely origin of the
rotation observed for the Radio Arc NTFs; however, internal Faraday effects are
also found to be likely in regions of parallel magnetic field. The increased
likelihood of internal Faraday effects in parallel magnetic field regions may
be attributed to the effects of structures local to the GC. One such structure
could be the Radio Shell local to the Radio Arc NTFs. Future studies are needed
to determine whether this alternating magnetic field pattern is present in
other multi-stranded NTFs, or is a unique property resulting from the complex
interstellar region local to the Radio Arc NTFs.
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