The candidates for Class I methanol masers

TL;DR

This paper models the collisional excitation of methanol in shock waves to identify potential Class I methanol maser candidates, considering chemical processes and energy level populations.

Contribution

It provides a comprehensive shock model including chemical processes and predicts candidate transitions for Class I methanol masers based on collisional pumping.

Findings

List of candidate Class I methanol maser transitions

Optical depth calculations for inverted transitions

Identification of collisional pumping mechanisms

Abstract

The collisional excitation of methanol molecule in non-dissociative magnetohydrodynamic shock waves is considered. All essential chemical processes that determine methanol abundance in the gas are taken into account in the shock model. The large velocity gradient approximation is used in the calculations of energy level populations of the molecule. We calculate the optical depth for inverted methanol transitions, and present the list of candidates for Class I methanol masers that have collisional pumping mechanism.