The Megamaser Cosmology Project − XII. VLBI imaging of H2O maser emission in three active galaxies and the effect of AGN winds on disc dynamics

• Published in: Monthly notices of the Royal Astronomical Society 2020-10, Vol.498 (2), p.1609-1627
• Main Authors: Kuo, C Y, Braatz, J A, Impellizzeri, C M V, Gao, F, Pesce, D, Reid, M J, Condon, J, Kamali, F, Henkel, C, Greene, J E
• Format: Article
• Language: English
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/staa2260

ABSTRACT 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$\pm 0.2)\times 10^{7}\, \mathrm{ M}_{\odot }$. 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 $M_{\rm BH}\, \lt$ 8 × 106 M⊙ and Eddington ratios $\lambda _{\rm Edd}\, \gtrsim$ 0.1, while the triple-peaked megamasers show an opposite trend.