First Detection of the Zeeman Effect in the 36 GHz Class I methanol maser line with the EVLA

TL;DR

This paper reports the first detection of the Zeeman effect in the 36 GHz Class I methanol maser line, revealing magnetic field strengths in a star-forming region that are comparable to those in other methanol maser lines, indicating the magnetic field's dynamical importance.

Contribution

First detection of Zeeman effect in 36 GHz Class I methanol masers, providing new insights into magnetic fields in star-forming regions.

Findings

Detected magnetic fields of -31.3 and 20.2 mG in M8E.

Magnetic fields are comparable to those in 6.7 GHz masers.

Magnetic field is dynamically significant in the region.

Abstract

We report the first detection of the Zeeman effect in the 36 GHz Class I methanol maser line. The observations were carried out with 13 antennas of the EVLA toward the high mass star forming region M8E. Based on our adopted Zeeman splitting factor of $z = 1.7 Hz/mG, we detect a line of sight magnetic field of -31.3 +/- 3.5 mG and 20.2 +/- 3.5 mG to the northwest and southeast of the maser line peak respectively. This change in sign over a 1300 AU size scale may indicate that the masers are tracing two regions with different fields, or that the same field curves across the regions where the masers are being excited. The detected fields are not significantly different from the magnetic fields detected in the 6.7 GHz Class II methanol maser line, indicating that methanol masers may trace the large scale magnetic field, or that the magnetic field remains unchanged during the early evolution of star forming regions. Given what is known about the densities at which 36 GHz methanol masers are excited, we find that the magnetic field is dynamically significant in the star forming region.