Magnetic Field Configuration at the Galactic Center Investigated by Wide Field Near-Infrared Polarimetry: Transition from a Toroidal to a Poloidal Magnetic Field

TL;DR

This study maps the large-scale magnetic field in the Galactic Center, revealing a transition from a toroidal to a poloidal configuration with increasing latitude, using near-infrared polarimetry of dust grains.

Contribution

First observation of a smooth transition in the large-scale magnetic field configuration in the Galactic Center region.

Findings

Magnetic field is toroidal near the Galactic plane.

At higher latitudes, the magnetic field becomes poloidal.

The transition between configurations is smoothly observed.

Abstract

We present a large-scale view of the magnetic field in the central 2deg * 2deg region of our Galaxy. The polarization of point sources has been measured in the J, H, and Ks bands using the near-infrared polarimetric camera SIRPOL on the 1.4 m telescope IRSF. Comparing the Stokes parameters between high extinction stars and relatively low extinction ones, we obtain polarization originating from magnetically aligned dust grains in the central few-hundred pc of our Galaxy. We find that near the Galactic plane, the magnetic field is almost parallel to the Galactic plane (i.e., toroidal configuration) but at high Galactic latitudes (| b | > 0.4deg), the field is nearly perpendicular to the plane (i.e., poloidal configuration). This is the first detection of a smooth transition of the large-scale magnetic field configuration in this region.