Interferometric and single-dish observations of 44, 84 and 95 GHz Class I methanol masers

TL;DR

This study used interferometric and single-dish observations to detect and analyze Class I methanol masers at multiple frequencies in massive star-forming regions, revealing associations with outflows, HII regions, and shocks.

Contribution

It provides the first high-resolution interferometric mapping of 44 GHz methanol masers and explores their associations with various star formation phenomena.

Findings

53 out of 125 regions showed 44 GHz maser emission

High detection rates of 74% at 84.5 GHz and 100% at 96.7 GHz

Revealed associations of masers with outflows, HII regions, and shocks

Abstract

We present observations of massive star-forming regions selected from the IRAS Point Source Catalog. The observations were made with the Very Large Array and the Large Millimeter Telescope to search for Class I methanol masers. We made interferometric observations of 125 massive star-forming regions in the 44 GHz methanol maser transition; 53 of the 125 fields showed emission. The data allow us to demonstrate associations, at arcsecond precision, of the Class I maser emission with outflows, HII regions and shocks traced by 4.5 $\mu$m emission. We made single-dish observations toward 38 of 53 regions with 44 GHz masers detected to search for methanol transitions at 84.5, 95.1, 96.7, 107.0, and 108.8 GHz. We find detection rates of 74, 55, 100, 3, and 45%, respectively. We used a wide-band receiver which revealed many other spectral lines that are common in star-forming regions.