Magnetic field in mini starburst complex Sgr B2

TL;DR

This study presents high-resolution magnetic field observations in the Sgr B2 starburst complex, revealing magnetic strengths and a multi-scale gravitational collapse consistent with active star formation.

Contribution

First arcsecond-resolution polarization observations of Sgr B2's magnetic field, showing a multi-scale gravitational collapse and magnetic field strengths in dense cores.

Findings

Magnetic field strengths range from 1.9 to 14.7 mG in cores.

Magnetic conditions are supercritical from cloud to core scales.

Star formation likely driven by multi-scale gravitational collapse.

Abstract

We report the first arcsecond-resolution observations of the magnetic field in the mini starburst complex Sgr B2. SMA polarization observations revealed magnetic field morphology in three dense cores of Sgr B2 N(orth), M(ain), and S(outh). The total plane-of-sky magnetic field strengths in these cores are estimated to be 4.3-10.0 mG, 6.2-14.7 mG, and 1.9-4.5 mG derived from the angular dispersion function method after applying the correction factors of 0.21 and 0.5. Combining with analyses of the parsec-scale polarization data from SOFIA, we found that a magnetically supercritical condition is present from the cloud-scale ($\sim$10 pc) to core-scale ($\sim$0.2 pc) in Sgr B2, which is consistent with the burst of star formation activities in the region likely resulted from a multi-scale gravitational collapse from the cloud to dense cores.