Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· arXiv e-print (arXiv:0902.0978)
· On-line Data
· References in the article
· Citations to the Article (11) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (18)
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
The Role of Molecular Gas in Obscuring Seyfert Active Galactic Nuclei
Authors:
Hicks, E. K. S.; Davies, R. I.; Malkan, M. A.; Genzel, R.; Tacconi, L. J.; Sánchez, F. Müller; Sternberg, A.
Affiliation:
AA(Max Planck Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany ), AB(Max Planck Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany ), AC(Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1562, USA ), AD(Max Planck Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany ; Department of Physics, 366 Le Conte Hall, University of California, Berkeley, CA 94720-7300, USA ), AE(Max Planck Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany ), AF(Max Planck Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany ), AG(School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel)
Publication:
The Astrophysical Journal, Volume 696, Issue 1, pp. 448-470 (2009). (ApJ Homepage)
Publication Date:
05/2009
Origin:
IOP
ApJ Keywords:
galaxies: active, galaxies: kinematics and dynamics, galaxies: nuclei, galaxies: Seyfert, infrared: galaxies
DOI:
10.1088/0004-637X/696/1/448
Bibliographic Code:
2009ApJ...696..448H

Abstract

In a sample of local active galactic nuclei (AGNs) studied at a spatial resolution on the order of 10 pc, we show that the interstellar medium traced by the molecular hydrogen ν = 1-0 S(1) line at 2.1 μm forms a geometrically thick, clumpy disk. The kinematics of the molecular gas reveals general rotation, although an additional significant component of random bulk motion is required by the high local velocity dispersion. The size scale of the typical gas disk is found to have a radius of ~30 pc with a comparable vertical height. Within this radius, the average gas mass is estimated to be ~107 M sun based on a typical gas mass fraction of 10%, which suggests column densities of N H ~ 5 × 1023 cm-2. Extinction of the stellar continuum within this same region suggests lower column densities of N H ~2 × 1022 cm-2, indicating that the gas distribution on these scales is dominated by dense clumps. In half of the observed Seyfert galaxies, this lower column density is still great enough to obscure the AGN at optical/infrared wavelengths. We conclude, based on the spatial distribution, kinematics, and column densities that the molecular gas observed is spatially mixed with the nuclear stellar population and is likely to be associated with the outer extent of any smaller scale nuclear obscuring structure. Furthermore, we find that the velocity dispersion of the molecular gas is correlated with the star formation rate per unit area, suggesting a link between the two phenomena, and that the gas surface density follows known "Schmidt-Kennicutt" relations. The molecular/dusty structure on these scales may be dynamic since it is possible that the velocity dispersion of the gas, and hence the vertical disk height, is maintained by a short, massive inflow of material into the nuclear region and/or by intense, short-lived nuclear star formation.

Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints