The Infrared Continuum of Active Galaxies

Abstract

We discuss the different physical processes contributing to the infrared continuum of AGN, assuming that both photoionization from the active center and shocks ionize and heat the gas and dust contained in an ensemble of clouds surrounding the nucleus. Radiation transfer of primary and secondary radiation throughout a cloud is calculated consistently with collisional processes due to the shock. We consider that the observed continuum corresponds to reprocessed radiation from both dust and gas in the clouds. The model is applied to the continuum of Seyfert galaxies from which best estimate of the nuclear, stellar subtracted, emission is available. The results show that radiation-dominated high velocity clouds are more numerous in Seyfert 1-1.5 whereas shock-dominated low velocity clouds are dominant in Seyfert type 2 in full agreement with the unified model for AGN. In type 2 objects, radiation is partly suppressed by a central dusty medium with a high dust-to-gas ratio. A grid of models is used to provide a phenomenological analysis of the observed infrared spectral energy distribution.

14 pages, 10 figures. in press in MNRAS

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Cited by in corpus (18)

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• The Infrared Emission from the Narrow Line Region
• Unveiling the central parsec region of an AGN: the Circinus nucleus in the near infrared with the VLT
• Morphology of the coronal line region in active galactic nuclei
• VLT diffraction-limited imaging at 11 and 18 micron of the nearest active galactic nuclei
• The continuum and narrow line region of the NLS1 galaxy Mrk 766
• Optical and mid-infrared line emission in nearby Seyfert galaxies
• The complex structure of low luminosity AGN : NGC 4579
• An analysis of infrared emission spectra from the regions near the Galactic Center
• Evidences of merging in the Seyfert galaxy NGC 3393 revealed by modelling the spectra
• Dust-to-gas ratios in the Kepler supernova remnant
• Gas and dust spectra of the D' type symbiotic star HD330036
• The merger Seyfert galaxy Arp 220. Line and continuum absorption and emission
• Distribution of the heavy elements throughout the extended narrow line region of the Seyfert galaxy NGC 7212
• The LLAGN in the centre of the Galaxy
• Metallicity in the merger Seyfert galaxy NGC 6240
• Comparison of dust-to-gas ratios in luminous, ultraluminous, and hyperluminous infrared galaxies