1 research outputs found
High-sensitivity VLBI Observations of the Water Masers in the Seyfert Galaxy NGC 1068
We present observational results of water vapor maser emission with our
high-sensitivity 22 GHz VLBI imaging of the Seyfert galaxy NGC 1068. In this
galaxy, there are the following four nuclear radio sources; NE, C, S1, and S2.
Among them, the S1 component has been identified as the nucleus while the C
component has been considered as attributed to the radio jet. In our VLBI
observation, we find the following two types of the water maser emission at the
S1 component. One is the linearly aligned component that is considered as an
edge-on disk with the inner radius of 0.62 pc. The dynamical mass enclosed
within the inner radius was estimated to be by
assuming the circular Keplerian motion. Note, however, that the best fit
rotation curve shows a sub-Keplerian rotation ().
The other is the water maser emission distributed around the rotating disk
component up to 1.5 pc from the S1 component, suggesting the bipolar outflow
from the S1 component. Further, we detected the water maser emission in the C
component for the first time with VLBI, and discovered a ring-like distribution
of the water maser emission. It is known that a molecular cloud is associated
with the C component (both HCN and HCO emission lines are detected by
ALMA). Therefore, the ring-like maser emission can be explained by the jet
collision to the molecular cloud. However, if these ring-like water masing
clouds constitute a rotating ring around the C component, it is likely that the
C component also has a supermassive black hole with the mass of that could be supplied from a past minor merger of a nucleated
satellite galaxy.Comment: 16 pages, 10 figures, accepted for publication in the PAS