Hot-dust-poor type 1 active galactic nuclei in the COSMOS survey

Heng Hao; Martin Elvis; Francesca Civano; Giorgio Lanzuisi; Marcella Brusa; Elisabeta Lusso; Gianni Zamorani; Andrea Comastri; Angela Bongiorno; Chris D. Impey; Anton M. Koekemoer; Emeric Le Floc'h; Mara Salvato; David Sanders; Jonathan R. Trump; Cristian Vignali

doi:10.1088/2041-8205/724/1/L59

Hot-dust-poor type 1 active galactic nuclei in the COSMOS survey

Heng Hao, Martin Elvis, Francesca Civano, Giorgio Lanzuisi, Marcella Brusa, Elisabeta Lusso, Gianni Zamorani, Andrea Comastri, Angela Bongiorno, Chris D. Impey, Anton M. Koekemoer, Emeric Le Floc'h, Mara Salvato, David Sanders, Jonathan R. Trump, Cristian Vignali

Astronomy

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Abstract

We report a sizable class of type 1 active galactic nuclei (AGNs) with unusually weak near-infrared (1-3μm) 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 3μm emission relative to the 1μmemission is a factor of 2-4 smaller than the typical Elvis et al.AGNspectral 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) × 10⁴ Schwarzschild radii, ∼10-23 times the gravitational stability radii. Formation scenarios for these sources are discussed.

Original language	English (US)
Pages (from-to)	L59-L63
Journal	Astrophysical Journal Letters
Volume	724
Issue number	1 PART 2
DOIs	https://doi.org/10.1088/2041-8205/724/1/L59
State	Published - Nov 20 2010

Keywords

Galaxies: evolution
Quasars: general

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/2041-8205/724/1/L59

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Hao, H., Elvis, M., Civano, F., Lanzuisi, G., Brusa, M., Lusso, E., Zamorani, G., Comastri, A., Bongiorno, A., Impey, C. D., Koekemoer, A. M., Le Floc'h, E., Salvato, M., Sanders, D., Trump, J. R., & Vignali, C. (2010). Hot-dust-poor type 1 active galactic nuclei in the COSMOS survey. Astrophysical Journal Letters, 724(1 PART 2), L59-L63. https://doi.org/10.1088/2041-8205/724/1/L59

Hao, H, Elvis, M, Civano, F, Lanzuisi, G, Brusa, M, Lusso, E, Zamorani, G, Comastri, A, Bongiorno, A, Impey, CD, Koekemoer, AM, Le Floc'h, E, Salvato, M, Sanders, D, Trump, JR & Vignali, C 2010, 'Hot-dust-poor type 1 active galactic nuclei in the COSMOS survey', Astrophysical Journal Letters, vol. 724, no. 1 PART 2, pp. L59-L63. https://doi.org/10.1088/2041-8205/724/1/L59

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abstract = "We report a sizable class of type 1 active galactic nuclei (AGNs) with unusually weak near-infrared (1-3μm) 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 3μm emission relative to the 1μmemission is a factor of 2-4 smaller than the typical Elvis et al.AGNspectral 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) × 104 Schwarzschild radii, ∼10-23 times the gravitational stability radii. Formation scenarios for these sources are discussed.",

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AU - Hao, Heng

AU - Elvis, Martin

AU - Civano, Francesca

AU - Lanzuisi, Giorgio

AU - Brusa, Marcella

AU - Lusso, Elisabeta

AU - Zamorani, Gianni

AU - Comastri, Andrea

AU - Bongiorno, Angela

AU - Impey, Chris D.

AU - Koekemoer, Anton M.

AU - Le Floc'h, Emeric

AU - Salvato, Mara

AU - Sanders, David

AU - Trump, Jonathan R.

AU - Vignali, Cristian

PY - 2010/11/20

Y1 - 2010/11/20

N2 - We report a sizable class of type 1 active galactic nuclei (AGNs) with unusually weak near-infrared (1-3μm) 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 3μm emission relative to the 1μmemission is a factor of 2-4 smaller than the typical Elvis et al.AGNspectral 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) × 104 Schwarzschild radii, ∼10-23 times the gravitational stability radii. Formation scenarios for these sources are discussed.

AB - We report a sizable class of type 1 active galactic nuclei (AGNs) with unusually weak near-infrared (1-3μm) 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 3μm emission relative to the 1μmemission is a factor of 2-4 smaller than the typical Elvis et al.AGNspectral 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) × 104 Schwarzschild radii, ∼10-23 times the gravitational stability radii. Formation scenarios for these sources are discussed.

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KW - Quasars: general

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Hot-dust-poor type 1 active galactic nuclei in the COSMOS survey

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Keywords

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