High Spatial Resolution Mid-Infrared Observations of Three Seyfert Galaxies
Author(s) -
B. T. Soifer,
J. Böck,
K. A. Marsh,
G. Neugebauer,
K. Matthews,
E. Egami,
L. Armus
Publication year - 2003
Publication title -
the astronomical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.61
H-Index - 271
eISSN - 1538-3881
pISSN - 0004-6256
DOI - 10.1086/375647
Subject(s) - physics , astrophysics , galaxy , infrared , luminosity , millimeter , flux (metallurgy) , astronomy , brightness , surface brightness , angular resolution (graph drawing) , luminous infrared galaxy , star formation , angular diameter , wavelength , telescope , active galactic nucleus , optics , stars , materials science , mathematics , combinatorics , metallurgy
Images at 12.5 microns of nuclei of three nearby Seyfert galaxies -- NGC1275, NGC 4151 and NGC 7469 -- have been obtained with the Keck 10-m Telescope.NGC 7469 is resolved and deconvolution delineates a structure <0.04"x0.08" or<13x26 pc at a position angle of 135deg. From a comparison with structure seenat millimeter wavelengths, this structure is interpreted as a disk aligned withthe molecular gas in the central few hundred parsecs of the galaxy. NGC 1275and NGC 4151 are not resolved; limits on the sizes of these nuclei are 0.08"and 0.16", corresponding to physical spatial scales of 28 and 10 pc. The lowerlimits to the brightness temperatures implied by these size limits and themeasured flux densities are within ~50K of the 12 micron to 25 micron colortemperatures of these systems as inferred from IRAS observations. The angularsize limits are within a factor of 2.5 of the sizes required to spatiallyresolve thermal emission from dust heated by a central luminosity source. Thesesizes preclude significant contributions to the nuclear infrared emission fromstar forming regions.Comment: 23 pages, 7 figures, A.J. in pres
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