Properties of H2O Masers and Their Associated Sources in Sagittarius B2

We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz H2O maser line in the extended Sagittarius B2 cloud. We detect 499 H2O masers across the observed velocities between −39 and 172 km s−1. To investigate the nature of the masers, we analyze their spatial distribution and crossmatch with catalogs of H II regions and protostellar cores. 62% of masers are associated with protostellar cores and 32% with H II regions. The nature of the remaining 6% of sources was not established but is likely associated with protostellar cores. Based on the spatial extent of the groups of masers, we classify them as either outflow-associated or young stellar object (YSO)-associated. We identify 144 unique sites of maser emission: 23 are associated with H II regions and 94 with protostellar cores, of which 33 are associated with protostellar outflows and 18 with YSOs. The outflow-associated H2O maser emission is confined to within <2000 au of the central continuum source, despite shocked SiO emission extending over tens of thousands of astronomical units. The YSO-associated masers show a lack of detections at 5 < Vrel < 30 km s−1, which we suggest may be due to maser self-absorption. We show how H2O masers trace the large-scale material flow in Sgr B2 North, also seen in SiO and millimeter continuum emission. Finally, we find that protostellar cores with associated H2O masers tend to have brighter 3 mm continuum emission on average, although there is no strong correlation between maser brightness and continuum flux.