A search for water masers associated with class II methanol masers - II. Longitude range 341$^{\circ}$ to 6$^{\circ}$

TL;DR

This study surveys water masers associated with 6.7-GHz methanol masers in a specific galactic longitude range, finding about half have water masers, with minimal differences in properties and no clear evolutionary correlation.

Contribution

It provides the second catalog of water masers linked to methanol masers in the specified longitude, expanding understanding of their association and properties in this region.

Findings

Approximately 50% of methanol masers have associated water masers.

No significant difference in luminosities between sources with and without water masers.

Water masers are less tightly correlated with YSO evolution than methanol masers.

Abstract

This is the second paper in a series of catalogues of 22-GHz water maser observations towards the 6.7-GHz methanol masers from the Methanol Multibeam (MMB) Survey. In this paper we present our water maser observations made with the Australia Telescope Compact Array towards the masers from the MMB survey between l = 341$^{\circ}$ through the Galactic centre to l = 6$^{\circ}$. Of the 204 6.7-GHz methanol masers in this longitude range we found 101 to have associated water maser emission (~ 50 per cent). We found no difference in the 6.7-GHz methanol maser luminosities of those with and without water masers. In sources where both maser species are observed, the luminosities of the methanol and water masers are weakly correlated. Studying the mid-infrared colours from GLIMPSE we found no differences between the colours of those sources associated with both methanol and water masers and those associated with just methanol. Comparing the column density and dust mass calculated from the 870-micron thermal dust emission observed by ATLASGAL, we found no differences between those sources associated with both water and methanol masers and those with methanol only. Since water masers are collisionally pumped and often show emission further away from their accompanying YSO than the radiatively pumped 6.7-GHz methanol masers, it is likely water masers are not as tightly correlated to the evolution of the parent YSO and so do not trace such a well defined evolutionary state as 6.7-GHz methanol masers.