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Date and Time of the Query: 2019-06-25 T14:38:55 PDT
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For refcode 1992ApJ...395L..73S:
Retrieve 9 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1992ApJ...395L..73S INFRARED EMISSION IN SEYFERT 2 GALAXIES: REPROCESSED RADIATION FROM A DUSTY TORUS? THAISA STORCHI-BERGMANN Instituto de Fisica, UFRGS, Campus do Vale, 91500 Porto Alegre, RS, Brazil; and Astronomy Department, University of Maryland AND JOHN S. MULCHAEY AND ANDREW S. WILSON Astronomy Department University of Maryland; and Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 Received 1992 April 28; accepted 1992 June 4 ABSTRACT The nature of the infrared continuum in Seyfert 2 galaxies is not well understood. An attractive model is one in which dust grains near the nucleus are heated by optical and ultraviolet photons from a central source and reradiate in the IR. However, a comparison of the observed optical-UV continuum with the observed IR emission indicates that in many Seyfert 2's there is a deficiency of dust heating photons. This apparent deficiency may be understood if the photons responsible for heating the dust escape anisotropically. Recent work has revealed that a number of Seyfert 2 galaxies exhibit conically shaped regions of gas apparently illuminated by a collimated, nuclear ionizing source. In this Letter, we test one model for this collimation, namely that the cones result from Shadowing of a compact nuclear continuum source by a thick, dusty torus. From the emission-line ratios measured for gas within the cones, we have calculated the number of ionizing photons emitted by the compact nucleus. Then, on the assumption that this compact nuclear source radiates isotropically, we have found the optical-UV power incident on the torus, which is expected to he reradiated in the IR. We find the observed IRAS luminosities are consistent with the torus model in eight of the nine objects with sufficient data to perform the calculation. Subject headings: galaxies: active - galaxies: nuclei - galaxies: Seyfert - infrared: galaxies
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