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Detailed Polarimetric Analysis of the Galactic Center Radio Arc

Presentation #330.07 in the session “The Milky Way and Galactic Center”.

Published onJun 18, 2021
Detailed Polarimetric Analysis of the Galactic Center Radio Arc

The Galactic Center (GC) is an unusual region of the Galaxy that contains a unique population of structures known as the non-thermal filaments (NTFs). The NTFs are highly polarized with polarized intensity which traces the total intensity of the NTFs. In addition, the intrinsic magnetic field of these structures is found to be parallel to the extent of the NTFs. The most prominent NTF, known as the Radio Arc, exhibits polarized intensity structures which extend into regions of low total intensity. In addition, the intrinsic magnetic field distribution alternates between being parallel and rotated with respect to the orientation of the total intensity of the Radio Arc. The origin of these unusual features for the Radio Arc remains unclear. We obtained an Australia Telescope Compact Array (ATCA) data set of the Radio Arc ranging from 4–11 GHz to probe the mechanisms responsible for the unique features seen for the Radio Arc. Using the 1 MHz spectral resolution of our ATCA data, we probe the spectral variance of the polarization data of the Radio Arc. Using this spectral data, we fit models of key depolarization mechanisms responsible for the rotation of the polarized emission observed towards the Radio Arc. This model fitting of the data allows us to analyze the number and nature of rotating media located along the line of sight. This analysis allows us to probe whether an additional intervening medium is responsible for the unusual polarized intensity and magnetic field properties observed for the Radio Arc. This work expands our understanding of the environment local to the Radio Arc while also illuminating the mechanisms responsible for this prominent NTF system.

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