Publication Date:
2020-08-18
Description:
We present very long baseline interferometry (VLBI) images and kinematics of water maser emission in three active galaxies: NGC 5728, Mrk 1, and IRAS 08452–0011. IRAS 08452–0011, at a distance of ∼200 Mpc, is a triple-peaked H2O megamaser, consistent with a Keplerian rotating disc, indicating a black hole mass of (3.3$pm 0.2)imes 10^{7}, mathrm{ M}_{odot }$. NGC 5728 and Mrk 1 display double-peaked spectra, and VLBI imaging reveals complicated gas kinematics that do not allow for a robust determination of black hole mass. We show evidence that the masers in NGC 5728 are in a wind while the Mrk 1 maser system has both disc and outflow components. We also find that disturbed morphology and kinematics are a ubiquitous feature of all double-peaked maser systems, implying that these maser sources may reside in environments where active galactic nucleus (AGN) winds are prominent at ∼1 pc scale and have significant impact on the masing gas. Such AGNs tend to have black hole masses $M_{
m BH}, lt$ 8 × 106 M⊙ and Eddington ratios $lambda _{
m Edd}, gtrsim$ 0.1, while the triple-peaked megamasers show an opposite trend.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics