Analyzing the Intrinsic Magnetic Field in the Galactic Center Radio Arc

Abstract

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.

References in corpus (22)

• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• Faraday Rotation Measure Synthesis
• Relativistic redshift of the star S0-2 orbiting the Galactic center supermassive black hole
• HST/NICMOS Observations of Massive Stellar Clusters Near the Galactic Center
• Complex Faraday depth structure of Active Galactic Nuclei as revealed by broadband radio polarimetry
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event
• The spiral structure of our Milky Way Galaxy
• Pulsar Rotation Measures and Large-scale Magnetic Field Reversals in the Galactic Disk
• A Radio Polarimetric Study of the Galactic Center Threads
• Interstellar magnetic fields in the Galactic center region
• Discovery of a Non-Thermal Galactic Center Filament (G358.85+0.47) Parallel to the Galactic Plane
• Spitzer IRS Observations of the Galactic Center: Shocked Gas in the Radio Arc Bubble
• Broadband, radio spectro-polarimetric study of 100 radiative-mode and jet-mode AGN
• Faraday Rotation Measure Synthesis for Magnetic Fields of Galaxies
• The Galactic center chimneys: The base of the multiphase outflow of the Milky Way
• The Atacama Cosmology Telescope: Microwave Intensity and Polarization Maps of the Galactic Center
• Faraday rotation at low frequencies: magnetoionic material of the large FRII radio galaxy PKS J0636-2036
• A VLA Polarimetric Study of the Galactic Center Radio Arc: Characterizing Polarization, Rotation Measure, and Magnetic Field Properties
• M0.20-0.033: An Expanding Molecular Shell in the Galactic Center Radio Arc
• The Q/U Imaging ExperimenT: Polarization Measurements of the Galactic Plane at 43 and 95 GHz
• Revealing the Faraday Depth Structure of Radio Galaxy NGC 612 with Broad-Band Radio Polarimetric Observations

Cited by in corpus (5)

• The MPIfR-MeerKAT Galactic Plane survey I -- System setup and early results
• SOFIA/HAWC+ Far-InfraRed Polarimetric Large Area CMZ Exploration (FIREPLACE) Survey I: General Results from the Pilot Program
• Rotation measure variations in Galactic Centre pulsars
• Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13-0.11: Proof of the synchrotron nature by IXPE
• A VLA Study of Newly-Discovered Southern Latitude Non-Thermal Filaments in the Galactic Center: Radio Continuum Total-intensity and Spectral Index Properties