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Titolo:
The 9.7 micron silicate dust absorption toward the Cygnus A nucleus and the inferred location of the obscuring dust
Autore:
Imanishi, M; Ueno, S;
Indirizzi:
Natl Astron Observ, Mitaka, Tokyo 1818588, Japan Natl Astron Observ Mitaka Tokyo Japan 1818588 itaka, Tokyo 1818588, Japan Natl Spac Dev Agcy Japan, Tsukuba Space Ctr, Space Utilizat Res Program, Tsukuba, Ibaraki 3058505, Japan Natl Spac Dev Agcy Japan Tsukuba Ibaraki Japan 3058505 aki 3058505, Japan
Titolo Testata:
ASTROPHYSICAL JOURNAL
fascicolo: 2, volume: 535, anno: 2000,
parte:, 1
pagine: 626 - 631
SICI:
0004-637X(20000601)535:2<626:T9MSDA>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
ULTRALUMINOUS IRAS GALAXIES; ACTIVE GALACTIC NUCLEI; X-RAY OBSERVATIONS; INFRARED GALAXIES; INTERSTELLAR GRAINS; EMISSION; PHOTOMETRY; CONTINUUM; REGIONS; MODELS;
Keywords:
galaxies : active; galaxies : individual (Cygnus A); galaxies : nuclei; infrared : galaxies;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Imanishi, M Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822USA Univ Hawaii 2680 Woodlawn Dr Honolulu HI USA 96822 I 96822 USA
Citazione:
M. Imanishi e S. Ueno, "The 9.7 micron silicate dust absorption toward the Cygnus A nucleus and the inferred location of the obscuring dust", ASTROPHYS J, 535(2), 2000, pp. 626-631

Abstract

We report the detection of a 9.7 mu m silicate dust absorption feature toward the Cygnus A nucleus. Its optical depth is, however, significantly smaller than that expected from the dust extinction toward the background L-band emission region (A(V) similar to 150 mag). We argue that the most likely explanation for the small optical depth is that the obscuring dust exists so close to the central engine that a temperature gradient occurs. Our calculation confirms that the small optical depth and the spectral energy distribution at 3-30 mu m can be quantitatively reproduced by this explanation. Combining this picture with the huge active galactic nucleus (AGN) luminosity, the emission properties of Cygnus A are consistent with those of a type 2 quasar, that is, a highly luminous AGN that is highly obscured (A(V) > 50mag) by a dusty torus with an inner radius of less than 10 pc and not by greater than a few hundred parsec scale dust in the host galaxy.

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Documento generato il 04/04/20 alle ore 11:45:08