Detection of new methanol maser transitions associated with G358.93-0.03

TL;DR

This paper reports the discovery of new methanol maser transitions in a star-forming region, revealing rapid flaring activity and the first detection of certain transitions, indicating complex maser phenomena in massive star formation.

Contribution

It presents the first detection of 12.229, 20.347, and 23.121 GHz methanol masers, and reports rapid flaring behavior, expanding understanding of maser activity in star-forming regions.

Findings

New methanol maser transitions detected at 12.178, 12.229, 20.347, and 23.121 GHz.

Flaring activity occurs on timescales of days, with some transitions increasing by over 700 times.

First report of 12.229 and 20.347 GHz masers, and only the fourth source with 23.121 GHz masers.

Abstract

We report the detection of new 12.178, 12.229, 20.347, and 23.121 GHz methanol masers in the massive star-forming region G358.93-0.03, which are flaring on similarly short timescales (days) as the 6.668 GHz methanol masers also associated with this source. The brightest 12.178 GHz channel increased by a factor of over 700 in just 50 d. The masers found in the 12.229 and 20.347 GHz methanol transitions are the first ever reported and this is only the fourth object to exhibit associated 23.121 GHz methanol masers. The 12.178 GHz methanol maser emission appears to have a higher flux density than that of the 6.668 GHz emission, which is unusual. No associated near-infrared flare counterpart was found, suggesting that the energy source of the flare is deeply embedded.