Circumnuclear molecular gas in megamaser disk galaxies NGC 4388 and NGC 1194

Journal Article · Fri Jun 20 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/788/2/145· OSTI ID:22356573

Greene, Jenny E. ^[1]; Seth, Anil ^[2]; Lyubenova, Mariya; Van de Ven, Glenn; Läsker, Ronald ^[3]; Walsh, Jonelle ^[4]

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1. Department of Astrophysics, Princeton University, Princeton, NJ 08540 (United States)
2. University of Utah, Salt Lake City, UT 84112 (United States)
3. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
4. Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States)

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.

• OSTI ID: 22356573
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 788; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
DISPERSIONS
EXCITATION
GALAXIES
GALAXY NUCLEI
MASERS
SPATIAL DISTRIBUTION
SPATIAL RESOLUTION
SPECTROSCOPY
TWO-DIMENSIONAL CALCULATIONS
VELOCITY