HOT-DUST-POOR TYPE 1 ACTIVE GALACTIC NUCLEI IN THE COSMOS SURVEY
| Autor: | Marcella Brusa, Angela Bongiorno, Anton M. Koekemoer, Giorgio Lanzuisi, Mara Salvato, Emeric Le Floc'h, Andrea Comastri, Francesca Civano, Heng Hao, Martin Elvis, Chris Impey, David B. Sanders, Jonathan R. Trump, Elisabeta Lusso, G. Zamorani, Cristian Vignali |
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| Rok vydání: | 2010 |
| Předmět: |
Physics
Galaxies: evolution Quasars: general Cosmology and Nongalactic Astrophysics (astro-ph.CO) Active galactic nucleus Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astronomy and Astrophysics Torus Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Redshift Accretion disc Space and Planetary Science Instability theory Spectral energy distribution Astrophysics::Earth and Planetary Astrophysics Schwarzschild radius Astrophysics::Galaxy Astrophysics Astrophysics - Cosmology and Nongalactic Astrophysics Dust emission |
| Zdroj: | The Astrophysical Journal. 724:L59-L63 |
| ISSN: | 2041-8213 2041-8205 |
| DOI: | 10.1088/2041-8205/724/1/l59 |
| Popis: | We report a sizable class of type 1 active galactic nuclei (AGNs) with unusually weak near-infrared (1-3{\mu}m) emission in the XMM-COSMOS type 1 AGN sample. The fraction of these "hot-dust-poor" AGNs increases with redshift from 6% at lowredshift (z < 2) to 20% at moderate high redshift (2 < z < 3.5). There is no clear trend of the fraction with other parameters: bolometric luminosity, Eddington ratio, black hole mass, and X-ray luminosity. The 3{\mu}m emission relative to the 1{\mu}m emission is a factor of 2-4 smaller than the typical Elvis et al. AGN spectral energy distribution (SED), which indicates a "torus" covering factor of 2%-29%, a factor of 3-40 smaller than required by unified models. The weak hot dust emission seems to expose an extension of the accretion disk continuum in some of the source SEDs. We estimate the outer edge of their accretion disks to lie at $(0.3-2.0) /times 10^4$ Schwarzschild radii, ~10-23 times the gravitational stability radii. Formation scenarios for these sources are discussed. Comment: 6 pages, 3 figures; ApJ, 724, L59 |
| Databáze: | OpenAIRE |
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