The 6-GHz methanol multibeam maser catalogue II: Galactic longitudes 6 to 20

TL;DR

This paper reports the discovery of 119 methanol masers in the Galactic plane between longitudes 6 and 20 degrees, including 42 new sources, highlighting their distribution and association with Galactic structures.

Contribution

It provides the second part of an unbiased survey of methanol masers in this region, including new detections and analysis of their Galactic distribution and associations.

Findings

119 maser sources detected, 42 are new

Masers are tightly confined to the Galactic plane

Identification of masers associated with the Galactic bar

Abstract

We present the second portion of an unbiased survey of the Galactic plane for 6668-MHz methanol masers. This section of the survey spans the longitude range 6 degrees to 20 degrees. We report the detection of 119 maser sources, of which 42 are new discoveries. The masers are tightly constrained to the Galactic plane, with only four outside a latitude range of +/- 1 degree. This longitude region includes the brightest known 6668-MHz methanol maser, 9.621+0.196, as well as the two brightest newly discovered sources in the southern survey as a whole. We list all the sources associated with the 3-kpc arms within +/- 15 degrees longitude and consider further candidates beyond 15 degrees longitude. We identify three new sources associated with the Galactic bar and comment on the density of masers in relation to the bar orientation.