Cosmic-ray driven outflow from the galactic center and the origin of magnetized radio filaments

TL;DR

This paper proposes that cosmic-ray driven winds from the Galactic center influence the magnetic field structure and formation of radio filaments, indicating recent starburst or black hole activity.

Contribution

It introduces a scenario where cosmic ray pressure drives large-scale winds that shape magnetic fields and filaments in the Galactic center, linking outflows to observed features.

Findings

Cosmic ray ionization rates are significantly higher in the Galactic center.

Wind interactions can explain the orientation of magnetized filaments.

Outflows may reduce gas and star formation in the central molecular zone.

Abstract

Radio, X-ray and infrared observations of the inner few hundred pc of the Galactic center have highlighted two characteristics to the ISM. The cosmic ray ionization rate derived from molecular ions such as H$^+_3$, is at least two to three orders of magnitudes higher than in the Galactic disk. The other is bipolar X-ray and radio emission away from the Galactic plane. These features are consistent with a scenario in which high cosmic ray pressure drives large-scale winds away from the Galactic plane. The interaction of such a wind with stellar wind bubbles may explain the energetic nonthermal radio filaments found throughout the Galactic center. Some of the implications of this scenario is the removal of gas driven by outflowing winds, acting as a feedback to reduce the star formation rate in the central molecular zone (CMZ), and the distortion of azimuthal magnetic field lines in the CMZ to vertical direction away from the plane. The combined effects of the wind and vertical magnetic field can explain why most magnetized filaments run perpendicular to the Galactic plane. This proposed picture suggests our Milky Way nucleus has recently experienced starburst or black hole activity, as recent radio and X-ray observations indicate.