The relative wavelength independence of IR lags in AGNs: implications for the distribu- tion of the hot dustтезисы доклада

Дата последнего поиска статьи во внешних источниках: 18 марта 2016 г.

Работа с тезисами доклада


[1] Oknyansky V. L., Gaskell C. M. The relative wavelength independence of ir lags in agns: implications for the distribu- tion of the hot dust // Torus 2015, Abstract book. — University of Southampton Southampton, UK, 2015. — P. 39–39. As seen from the central source, the dusty torus of AGNs has a puzzlingly high covering factor. If the torus consists of clouds of dust, each with a relatively unobscured view of the higher energy photons from nearer the center of the AGN, the temperature of each dust cloud will fall o as roughly the inverse square root of the radius. Since the dust is heated by the central radiation, in such a model the Near and Mid IR lag would increase with the wavelength to a power of 2 to 2.8. We show that, contrary to this simple prediction, for a signi cant fraction of AGNs the lags of the J, H, K, and L bands with respect to the optical show at best only a small di erence. This means that rather than there being an extended radial temperature gradient, the hot dust reprocessing the central radiation is e ectively in a relatively thin shell. We show that this can be explained by the hot dust being on the surface of a cone that is approximately tangential to the paraboloidal isodelay surface. We note that a number of the AGNs showing similar J, H, K, and L lags are also Seyferts that have changed between type 1 and type 2. It is not clear whether this is related or is merely a consequence of these objects being well studied for a long time.

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