期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 447, 期 3, 页码 2437-2444出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stu2566
关键词
dust, extinction; galaxies: nuclei; galaxies: Seyfert
资金
- CONA-CYT
- PA-PIIT, UNAM [IN107313]
- Alfred P. Sloan Foundation
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- University of Cambridge
- Case Western Reserve University
- University of Chicago
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck-Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- Ohio State University
- University of Pittsburgh
- University of Portsmouth
- Princeton University
- United States Naval Observatory
- University of Washington
We analyse the mid-infrared (MIR) spectra of 39 Seyfert galaxies observed with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. Our sample consists of 19 Seyfert type 1 (Sy1) galaxies, three intermediate Seyfert galaxies and 17 type 2 Seyfert (Sy2) galaxies in the nearby Universe. This sample was extracted from a larger sample, the circumgalactic environment of which was studied in a previous work by Dultzin-Hacyan et al., who found that Sy2 objects are in interaction more frequently than normal galaxies, while Sy1s are not. In this article, we study the silicate dust distribution that dominates the mid-infrared (MIR) spectra. This dust produces spectral features at 10 and 18 mu m that are sensitive to the clumpiness of the dust. We measure the strength of the emission or absorption of the silicate features to find whether there is a correlation between the clumpiness of the circumnuclear dust and the active galactic nucleus (AGN) type and incidence of companions. All isolated Sy1 galaxies have clumpy dust distributions, whereas Sy1s with a close companion can have either clumpy or smooth distributions. In the case of Sy2 galaxies, those with one or more companions have mostly smooth dust distributions, whereas isolated Sy2s may have clumpy or smoothly distributed dust. Our result is at odds with the simplest formulation of the unified scheme for Seyferts and supports an evolutionary sequence where the influence of an interaction triggers a type 2 AGN, which evolves into a type 1.
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