A MULTI-WAVELENGTH STUDY OF THE NATURE OF TYPE 1.8/1.9 SEYFERT GALAXIES

Journal Article · Mon Dec 20 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/2/1749· OSTI ID:21476687

Trippe, M L ^[1]; Crenshaw, D M ^[2]; Deo, R P ^[3]; Dietrich, M ^[4]; Kraemer, S B ^[5]; Rafter, S E ^[6]; Turner, T J ^[7]

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1. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
2. Department of Physics and Astronomy, Georgia State University, One Park Place South SE, Suite 700, Atlanta, GA 30303 (United States)
3. Department of Physics, Drexel University, Disque Hall, South 32nd Street, Rm. 813, Philadelphia, PA 19104 (United States)
4. Department of Astronomy, Ohio State University, 4055 McPherson Lab, 140 W. 18th Avenue, Columbus, OH 43210 (United States)
5. Institute for Astrophysics and Computational Sciences, Department of Physics, Catholic University of America, Washington, DC 20064 (United States)
6. Department of Physics, Technion, Haifa 32000 (Israel)
7. Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)

We focus on determining the underlying physical cause of a Seyfert galaxy's appearance as type 1.8 or 1.9. Are these 'intermediate' Seyfert types typical Seyfert 1 nuclei with reddened broad-line regions? Or are they objects with intrinsically weak continua and broad emission lines? We compare measurements of the optical reddening of the narrow and broad-line regions with each other and with the X-ray column derived from XMM-Newton 0.5-10 keV spectra to determine the presence and location of dust in the line of sight. We also searched the literature to see if the objects showed evidence for broad-line variability, and determined if the changes were consistent with a change in reddening or a change in the intrinsic ionizing continuum flux. We find that 10 of 19 objects previously classified as Seyfert 1.8/1.9s received this designation due to their low continuum flux. In four objects, the classification was due to broad emission-line region reddening, either by the torus or dust structures in the vicinity of the narrow emission-line region; in the remaining five objects there is not sufficient evidence to favor one scenario over the other. These findings imply that, in general, samples of 1.8/1.9s are not suitable for use in studies of gas and dust in the central torus.

• OSTI ID: 21476687
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 725; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DUSTS
EMISSION
GALAXIES
SEYFERT GALAXIES
WAVELENGTHS
X-RAY GALAXIES