Star Formation and AGN Contributions in the Water Maser Host Galaxy NGC 4945
Abstract
Constraining the respective contributions of active galactic nuclei (AGN) and star-forming activity is difficult even in nearby galaxies. Water maser emission at 22 GHz can trace warm, dense gas in both disks and outflows in AGN, and can be resolved in both position and velocity. One of the nearest starburst-AGN, NGC 4945, hosts both a kiloparsec-scale wind observed in the infrared, optical, and X-ray, and circumnuclear water masers in a pc-scale disk. Fitting Keplerian rotation curves to the high-velocity disk emission and requiring a consistent supermassive black hole (SMBH) mass from the red- and blue-shifted sides of the disk constrains the SMBH position. The nuclear maser emission also includes an arc immediately to the northwest of the maser-determined SMBH position. The arc agrees in direction and opening angle with the large scale wind, which suggests that it traces the base of the wind. This structure's proximity to the SMBH position suggests that the wind is AGN-driven. The disk contains additional velocity components that do not conform to these Keplerian curves, which may be from a fragmentation of the disk, possibly associated with star formation.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23523301R