Abstract
We explore the warm molecular and ionized gas in the centers of two
megamaser disk galaxies using K-band spectroscopy. Our ultimate goal is
to determine how gas is funneled onto the accretion disk, here traced by
megamaser spots on sub-parsec scales. We present NIR IFU data with a
resolution of ~50 pc for two galaxies: NGC 4388 with VLT/SINFONI and NGC
1194 with Keck/OSIRIS+AO. The high spatial resolution and rich spectral
diagnostics allow us to study both the stellar and gas kinematics as
well as gas excitation on scales only an order of magnitude larger than
the maser disk. We find a drop in the stellar velocity dispersion in the
inner ~100 pc of NGC 4388, a common signature of a dynamically cold
central component seen in many active nuclei. We also see evidence for
noncircular gas motions in the molecular hydrogen on similar scales,
with the gas kinematics on 100 parsec scales aligned with the megamaser
disk. In contrast, the high ionization lines and Brγ trace outflow
along the 100 parsec-scale jet. In NGC 1194, the continuum from the
accreting black hole is very strong, making it difficult to measure
robust two-dimensional kinematics, but the spatial distribution and line
ratios of the molecular hydrogen and Brγ have consistent
properties between the two galaxies.
Original language | English |
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Pages (from-to) | 145-158 |
Number of pages | 14 |
Journal | The Astrophysical Journal |
Volume | 788 |
Issue number | 2 |
DOIs | |
Publication status | Published - Jun-2014 |
Keywords
- galaxies: ISM
- galaxies: nuclei
- galaxies: Seyfert