English

Properties of $\mathrm{H_2O}$ masers and their associated sources in Sagittarius B2

Astrophysics of Galaxies 2025-07-01 v2

Abstract

We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz H2O\mathrm{H_2O} maser line in the extended Sagittarius B2 cloud. We detect 499 H2O\mathrm{H_2O} masers across the observed velocities between -39 and 172 km s1^{-1}. To investigate the nature of the masers, we analyze their spatial distribution and cross-match with catalogs of HII regions and protostellar cores. 62% of masers are associated with protostellar cores and 32% with HII 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 HII regions and 94 with protostellar cores, of which 33 are associated with protostellar outflows and 18 with YSOs. The outflow-associated H2O\mathrm{H_2O} maser emission is confined to within <2000<2000 au of the central continuum source, despite shocked SiO emission extending over tens of thousands of au. The YSO-associated masers show a lack of detections at 5<Vrel<305 < V_{rel} < 30 km s1^{-1}, which we suggest may be due to maser self-absorption. We show how H2O\mathrm{H_2O} masers trace the large-scale material flow in Sgr B2 N (North) also seen in SiO and mm continuum emission. Finally, we find that protostellar cores with associated H2O\mathrm{H_2O} masers tend to have brighter 3 mm continuum emission on average, although there is no strong correlation between maser brightness and continuum flux.

Keywords

Cite

@article{arxiv.2506.09115,
  title  = {Properties of $\mathrm{H_2O}$ masers and their associated sources in Sagittarius B2},
  author = {Nazar Budaiev and Adam Ginsburg and Ciriaco Goddi and Álvaro Sánchez-Monge and Anika Schmiedeke and Desmond Jeff and Peter Schilke and Christopher De Pree},
  journal= {arXiv preprint arXiv:2506.09115},
  year   = {2025}
}

Comments

20 pages, 18 figures. Accepted to ApJ