# Linear Polarization of Class I Methanol Masers in Massive Star-Forming Regions

## TL;DR

This study reports the first detection of linear polarization in 44 GHz Class I methanol masers, revealing insights into magnetic fields in massive star-forming regions through simultaneous observations at 44 and 95 GHz.

## Contribution

It provides the first polarization measurements of 44 GHz Class I methanol masers, comparing polarization properties at two frequencies to understand magnetic environments.

## Key findings

- Approximately 60% of sources show fractional polarization of a few percent.
- 44 and 95 GHz lines exhibit similar polarization properties.
- Some sources display polarization angle flips indicating complex magnetic structures.

## Abstract

Class I methanol masers are found to be good tracers of the interaction between outflows from massive young stellar objects with their surrounding media. Although polarization observations of Class II methanol masers have been able to provide information about magnetic fields close to the central (proto)stars, polarization observations of Class I methanol masers are rare, especially at 44 and 95 GHz. We present the results of linear polarization observations of 39 Class I methanol maser sources at 44 and 95 GHz. These two lines are observed simultaneously with one of the 21 m Korean VLBI Network telescopes in single-dish mode. Approximately 60% of the observed sources have fractional polarizations of a few percent in at least one transition. This is the first reported detection of linear polarization of the 44 GHz methanol maser. The two maser transitions show similar polarization properties, indicating that they trace similar magnetic environments, although the fraction of the linear polarization is slightly higher at 95 GHz. We discuss the association between the directions of polarization angles and outflows. We also discuss some targets having different polarization properties at both lines, including DR21(OH) and G82.58+0.20, which show the 90{\deg} polarization angle flip at 44 GHz.