Multiscale magnetic fields in the central molecular zone: inference from the gradient technique

Abstract

ABSTRACT The central molecular zone (CMZ) plays an essential role in regulating the nuclear ecosystem of our Galaxy. To get an insight into magnetic fields of the CMZ, we employ the gradient technique (GT), which is rooted in the anisotropy of magnetohydrodynamic turbulence. Our analysis is based on the data of multiple wavelengths, including molecular emission lines, radio 1.4 GHz continuum image, and Herschel $70\, {\mu }{\rm m}$ image, as well as ionized [Ne ii] and Paschen-alpha emissions. The results are compared with the observations of Planck 353 GHz and High-resolution Airborne Wideband Camera Plus (HWAC+) $53\, {\mu }{\rm m}$ polarized dust emissions. We map the magnetic fields orientation at multiple wavelength across the central molecular zone, including close-ups of the Radio Arc and Sagittarius A West regions, on multiscales from ∼0.1 pc to 10 pc. The magnetic fields towards the central molecular zone traced by the GT are globally compatible with the polarization measurements, accounting for the contribution from the galactic foreground and background. This correspondence suggests that the magnetic field and turbulence are dynamically crucial in the galactic center. We find that the magnetic fields associated with the Arched filaments and the thermal components of the Radio Arc are in good agree with the HAWC+ polarization. Our measurement towards the non-thermal Radio Arc reveals the poloidal magnetic field components in the galactic center. For Sagittarius A West region, we find a great agreement between the GT measurement using [Ne ii] emission and HWAC+ $53\, {\mu }{\rm m}$ observation. We use the GT to predict the magnetic fields associated with ionized Paschen-alpha gas down to scales of 0.1 pc.