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Title: A TALE OF THREE GALAXIES: ANOMALOUS DUST PROPERTIES IN IRAS F10398+1455, IRAS F21013–0739, AND SDSS J0808+3948

On a galactic scale, the 9.7 μm silicate emission is usually only seen in type 1 active galactic nuclei (AGNs). They usually also display a flat emission continuum at ∼5-8 μm and the absence of polycyclic aromatic hydrocarbon (PAH) emission bands. In contrast, starburst galaxies, luminous infrared (IR) galaxies, and ultraluminous IR galaxies exhibit a red 5-8 μm emission continuum, strong 9.7 μm and 18 μm silicate absorption features, and strong PAH emission bands. Here, we report the detection of anomalous dust properties by the Spitzer/Infrared Spectrograph in three galaxies (IRAS F10398+1455, IRAS F21013-0739, and SDSS J0808+3948) which are characterized by the simultaneous detection of a red 5-8 μm emission continuum, the 9.7 and 18 μm silicate emission features, as well as strong PAH emission bands. These apparently contradictory dust IR emission properties are discussed in terms of iron-poor silicate composition, carbon dust deficit, small grain size, and low dust temperature in the young AGN phase of these three galaxies.
Authors:
;  [1] ;  [2]
  1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)
  2. Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)
Publication Date:
OSTI Identifier:
22364933
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 794; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; COSMIC DUST; DETECTION; GALAXIES; GALAXY NUCLEI; GRAIN SIZE; INFRARED RADIATION; IRON; PHOTON EMISSION; POLYCYCLIC AROMATIC HYDROCARBONS; SILICATES