Physical conditions around 6.7 GHz methanol masers-I: Ammonia

TL;DR

This study investigates the physical conditions of star-forming regions associated with 6.7 GHz methanol masers by analyzing ammonia transitions, revealing higher temperatures than in dark clouds and minimal differences based on maser luminosity.

Contribution

It provides new insights into the physical environment of methanol masers, especially regarding temperature and line width correlations, using ammonia observations.

Findings

Gas kinetic temperature is higher than in infrared dark clouds.

Weak correlation between maser luminosity and ammonia line width.

No significant differences between low and high luminosity masers.

Abstract

Methanol masers at 6.7 GHz are known to be tracers of high-mass star formation in our Galaxy. In this paper, we study the large scale physical conditions in the star forming clumps/cores associated with 6.7 GHz methanol masers using observations of the (1,1), (2,2) and (3,3) inversion transitions of ammonia with the Effelsberg telescope. The gas kinetic temperature is found to be higher than in infrared dark clouds, highlighting the relatively evolved nature of the maser sources. Other than a weak correlation between maser luminosity and the ammonia line width, we do not find any differences between low and high luminosity methanol masers.