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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2510.10354 |
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Table of Contents:
- We present the results of very long baseline interferometry (VLBI) observations of water vapor masers in the nucleus of the LINER galaxy NGC 7738. The red- and blue-shifted and newly detected systemic maser features show an almost edge-on disk located at a distance of ${0.031}\mbox{-}{0.222}$ pc from the galactic center and rotating with a velocity of $324\mbox{-}454$ km s$^{-1}$ . The velocity field of the disk indicates sub-Keplerian rotation, suggesting a non-negligible disk mass. The Mestel disk model reveals the central and disk masses to be $(1.2 \pm 0.4) \times 10^6$ $M_{\odot}$ and $(4.7 \pm 1.5) \times10^6$ $M_{\odot}$, respectively. The mean volume density within the inner radius of the disk [$(1.2 \pm 0.5) \times 10^{10}$ $M_{\odot}$ $\mathrm{pc^{-3}}$] strongly suggests the existence of a supermassive black hole at the center.