An Outflow-Driven Water Maser Associated with Positive Black Hole Feedback in the Dwarf Galaxy Henize 2-10

TL;DR

This study uses high-resolution radio observations to identify two water maser sources in Henize 2-10, linking one to black hole outflow feedback and star formation, revealing the first such connection in a dwarf galaxy.

Contribution

It provides the first high-resolution imaging that confirms outflow-driven water masers are associated with positive black hole feedback in a dwarf galaxy.

Findings

Two distinct maser sources identified with different origins.

One maser linked to black hole outflow and star formation interface.

First evidence of outflow-driven H2O masers connected to positive BH feedback.

Abstract

Henize 2-10 is a dwarf galaxy experiencing positive black hole (BH) feedback from a radio-detected low-luminosity active galactic nucleus. Previous Green Bank Telescope (GBT) observations detected a H2O "kilomaser" in Henize 2-10, but the low angular resolution (33") left the location and origin of the maser ambiguous. We present new Karl G. Jansky Very Large Array observations of the H2O maser line at 22.23508 GHz in Henize 2-10 with ~2" resolution. These observations reveal two maser sources distinct in position and velocity. The first maser source is spatially coincident with the known BH outflow and the region of triggered star formation ~70 pc to the east. Combined with the broad width of the maser (W50 ~ 66 km s-1), this confirms our hypothesis that part of the maser detected with the GBT is produced by the impact of the BH outflow shocking the dense molecular gas along the flow and at the interface of the eastern star-forming region. The second maser source lies to the south-east far from the central BH and has a narrow width (W50 ~ 8 km s-1), suggesting a star-formation-related origin. This work has revealed the nature of the H2O kilomaser in Henize 2-10 and illustrates the first known connection between outflow-driven H2O masers and positive BH feedback.