SWAG Water Masers in the Galactic Center

TL;DR

This study maps water masers in the Galactic Center using the Australia Telescope, revealing their association with star formation and evolved stars, and providing insights into the region's complex gas dynamics.

Contribution

It presents the first large-scale, high-resolution survey of water masers in the Galactic Center, linking maser luminosities to star formation activity and stellar evolution.

Findings

Approximately 600 water masers detected.

High-luminosity masers linked to young stellar objects.

Lower-luminosity masers associated with evolved stars.

Abstract

The Galactic Center contains large amounts of molecular and ionized gas as well as a plethora of energetic objects. Water masers are an extinction-insensitive probe for star formation and thus ideal for studies of star formation stages in this highly obscured region. With the Australia Telescope Compact Array, we observed 22 GHz water masers in the entire Central Molecular Zone with sub-parsec resolution as part of the large SWAG survey: ``Survey of Water and Ammonia in the Galactic Center''. We detect of order 600 22 GHz masers with isotropic luminosities down to ~10^-7 Lo. Masers with luminosities of >~10^-6 Lo are likely associated with young stellar objects. They appear to be close to molecular gas streamers and may be due to star formation events that are triggered at pericenter passages near Sgr A*. Weaker masers are more widely distributed and frequently show double line features, a tell-tale sign for an origin in evolved star envelopes.