Abstract:
The Galactic Center (GC) is a unique observational target containing
molecular cloud densities, magnetic field strengths, and gas
temperatures more extreme than found elsewhere in the Galaxy. One way
to study the properties of the strong magnetic field in this region is
to analyze the unique non-thermal filaments (NTFs) -- extended,
synchrotron-emitting structures. The most prominent set of NTFs is
known as the Radio Arc. I conducted a radio polarimetric study of the
Radio Arc utilizing the S-, C-, and X-bands of the upgraded Very Large
Array interferometer, providing a multi-GHz frequency range with
hundreds of channels. In this talk I present the results of this study
and compare my findings with those obtained for other NTFs in the
GC. The total intensity distributions reveal large-scale helical
features that surround the Arc NTFs, very narrow sub-filamentation
within the Arc NTFs, and compact sources along the NTFs. The polarized
intensity is confined within a 4’ region of the Arc NTFs and there are
elongated polarized structure that appear to lack total intensity
counterparts. RM values towards the Radio Arc range from -500 to -5800
rad m-2, likely caused by external Faraday rotation along the line of
sight. After correcting for Faraday rotation, the intrinsic magnetic
field orientation is found to generally trace the extent of the
NTFs. However, the intrinsic magnetic field in several regions of the
Radio Arc shows an ordered pattern that is rotated by about 60° to the
extent of the NTFs. This changing pattern may be caused by an
additional magnetized local to the Radio Arc, so that we observe two
field systems superposed in our observations. The large-scale helical
segments near the Radio Arc could be components of such a source
causing these changes in intrinsic magnetic field, as well as some
variations in the polarization and rotation measure values along the
NTFs.
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