A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths
Autor(a) principal: | |
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Data de Publicação: | 1995 |
Outros Autores: | , , , , , , , , , , , , , , , , , , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/98097 |
Resumo: | With the aim of better understanding the physical processes that produce the continuous emission in active galactic nuclei (AGNs), a snapshot of the overall continuous energy distribution of NGC 3783, from γ-ray to radio wavelengths, has been obtained within the framework of the World Astronomy Days. The data collected in this campaign are from GRO, ROSAT, Voyager 2, IUE, HST, ESO, CTIO, SAAO and the VLA. Great care has been taken in disentangling the genuine AGN continuous emission from other contributions: depending on the waveband, the latter might be (i) unrelated contaminating sources in cases where the instrument field of view is large, (ii) components within which the AGN is embedded, such as the stellar bulge population which accounts for a significant fraction of the optical continuum, and free-bound and FeII blends which contribute to the ultraviolet flux. After correction for these other contributions, the continuous emission of the isolated AGN appears to be rather ftat (i.e., approximately equal energy per unit logarithmic frequency) from soft γ-ray to infrared wavelengths. At high energies (0.1 MeV to 0.1 keV), the AGN continuum can be fitted by a power law Fv ∝ v-α with a spectral index α ≈ 1. At longer wavelengths, two excesses above this power law ("bumps") appear: in the ultraviolet, the classical big blue bump, which can be interpreted as thermal emission from the accretion disc surrounding a massive black hoJe, and in the infrared a second bump which can be ascribed to thermal emission from dust in the vicinity of the AGN, heated by ultraviolet radiation from the central source. By fitting accretion-disc models to the observed AGN spectral energy distribution, we find values for the accretion disc innermost temperature, accretion rate, and black hole mass, with some differences that depend on whether or not we extrapolate the high-energy power law up to infrared wavelengths. A fit to the IR bump above the extended a = 1 power law suggests the presence of a dust component covering the region from a distance r ≈ 80 light days (hot grains at a temperature T ≈ 1500 K) to r ≈ 60 light years (cool grains at T ≈ 200 K). The total mass of dust is around 60 Mʘ. |
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Alloin, Danielle MarieSantos-Lleo, M.Peterson, Bradley M.Wamsteker, W.Altieri, B.Brinkmann, W.Crenshaw, Daniel MichaelGeorge, I.M.Clavel, J.Glass, I.S.Johnson, W.N.Kriss, Gerard A.Malkan, M.A.Polidan, R.S.Reichert, G.A.Rodriguez-Pascual, P.M.Romanishin, W.Starr, C.H.Stirpe, Giovanna M.Taylor, M.Turner, T.J.Vega, H.J. deWinge, ClaudiaWood, D.O.S.2014-07-18T02:04:39Z19950004-6361http://hdl.handle.net/10183/98097000263014With the aim of better understanding the physical processes that produce the continuous emission in active galactic nuclei (AGNs), a snapshot of the overall continuous energy distribution of NGC 3783, from γ-ray to radio wavelengths, has been obtained within the framework of the World Astronomy Days. The data collected in this campaign are from GRO, ROSAT, Voyager 2, IUE, HST, ESO, CTIO, SAAO and the VLA. Great care has been taken in disentangling the genuine AGN continuous emission from other contributions: depending on the waveband, the latter might be (i) unrelated contaminating sources in cases where the instrument field of view is large, (ii) components within which the AGN is embedded, such as the stellar bulge population which accounts for a significant fraction of the optical continuum, and free-bound and FeII blends which contribute to the ultraviolet flux. After correction for these other contributions, the continuous emission of the isolated AGN appears to be rather ftat (i.e., approximately equal energy per unit logarithmic frequency) from soft γ-ray to infrared wavelengths. At high energies (0.1 MeV to 0.1 keV), the AGN continuum can be fitted by a power law Fv ∝ v-α with a spectral index α ≈ 1. At longer wavelengths, two excesses above this power law ("bumps") appear: in the ultraviolet, the classical big blue bump, which can be interpreted as thermal emission from the accretion disc surrounding a massive black hoJe, and in the infrared a second bump which can be ascribed to thermal emission from dust in the vicinity of the AGN, heated by ultraviolet radiation from the central source. By fitting accretion-disc models to the observed AGN spectral energy distribution, we find values for the accretion disc innermost temperature, accretion rate, and black hole mass, with some differences that depend on whether or not we extrapolate the high-energy power law up to infrared wavelengths. A fit to the IR bump above the extended a = 1 power law suggests the presence of a dust component covering the region from a distance r ≈ 80 light days (hot grains at a temperature T ≈ 1500 K) to r ≈ 60 light years (cool grains at T ≈ 200 K). The total mass of dust is around 60 Mʘ.application/pdfengAstronomy and Astrophysics. Berlin. Vol. 293, no. 2 (Jan. 1995), p. 293-308Astrofisica extragalaticaGaláxia NGC 3783Nucleo galaticoGalaxias seyfertBuracos negrosGalaxies: SeyfertGalaxies: individual: NGC 3783Galaxies: nucleiRadiation mechanisms: non-thermalRadiation mechanisms: thermalBlack hole physicsA snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengthsEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL000263014.pdf000263014.pdfTexto completo (inglês)application/pdf394063http://www.lume.ufrgs.br/bitstream/10183/98097/1/000263014.pdff5f337cc9e188d960c53f9d982fda533MD51TEXT000263014.pdf.txt000263014.pdf.txtExtracted Texttext/plain352http://www.lume.ufrgs.br/bitstream/10183/98097/2/000263014.pdf.txt907636cc5f486b7825cfb9e5cab434b9MD52THUMBNAIL000263014.pdf.jpg000263014.pdf.jpgGenerated Thumbnailimage/jpeg1987http://www.lume.ufrgs.br/bitstream/10183/98097/3/000263014.pdf.jpga7c155d358166ffb4f30473e99347068MD5310183/980972018-10-19 10:53:45.393oai:www.lume.ufrgs.br:10183/98097Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2018-10-19T13:53:45Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
title |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
spellingShingle |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths Alloin, Danielle Marie Astrofisica extragalatica Galáxia NGC 3783 Nucleo galatico Galaxias seyfert Buracos negros Galaxies: Seyfert Galaxies: individual: NGC 3783 Galaxies: nuclei Radiation mechanisms: non-thermal Radiation mechanisms: thermal Black hole physics |
title_short |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
title_full |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
title_fullStr |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
title_full_unstemmed |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
title_sort |
A snapshot of the continuous emission of the active galactic nucleus in ngc 3783 from gamma-ray to radio wavelengths |
author |
Alloin, Danielle Marie |
author_facet |
Alloin, Danielle Marie Santos-Lleo, M. Peterson, Bradley M. Wamsteker, W. Altieri, B. Brinkmann, W. Crenshaw, Daniel Michael George, I.M. Clavel, J. Glass, I.S. Johnson, W.N. Kriss, Gerard A. Malkan, M.A. Polidan, R.S. Reichert, G.A. Rodriguez-Pascual, P.M. Romanishin, W. Starr, C.H. Stirpe, Giovanna M. Taylor, M. Turner, T.J. Vega, H.J. de Winge, Claudia Wood, D.O.S. |
author_role |
author |
author2 |
Santos-Lleo, M. Peterson, Bradley M. Wamsteker, W. Altieri, B. Brinkmann, W. Crenshaw, Daniel Michael George, I.M. Clavel, J. Glass, I.S. Johnson, W.N. Kriss, Gerard A. Malkan, M.A. Polidan, R.S. Reichert, G.A. Rodriguez-Pascual, P.M. Romanishin, W. Starr, C.H. Stirpe, Giovanna M. Taylor, M. Turner, T.J. Vega, H.J. de Winge, Claudia Wood, D.O.S. |
author2_role |
author author author author author author author author author author author author author author author author author author author author author author author |
dc.contributor.author.fl_str_mv |
Alloin, Danielle Marie Santos-Lleo, M. Peterson, Bradley M. Wamsteker, W. Altieri, B. Brinkmann, W. Crenshaw, Daniel Michael George, I.M. Clavel, J. Glass, I.S. Johnson, W.N. Kriss, Gerard A. Malkan, M.A. Polidan, R.S. Reichert, G.A. Rodriguez-Pascual, P.M. Romanishin, W. Starr, C.H. Stirpe, Giovanna M. Taylor, M. Turner, T.J. Vega, H.J. de Winge, Claudia Wood, D.O.S. |
dc.subject.por.fl_str_mv |
Astrofisica extragalatica Galáxia NGC 3783 Nucleo galatico Galaxias seyfert Buracos negros |
topic |
Astrofisica extragalatica Galáxia NGC 3783 Nucleo galatico Galaxias seyfert Buracos negros Galaxies: Seyfert Galaxies: individual: NGC 3783 Galaxies: nuclei Radiation mechanisms: non-thermal Radiation mechanisms: thermal Black hole physics |
dc.subject.eng.fl_str_mv |
Galaxies: Seyfert Galaxies: individual: NGC 3783 Galaxies: nuclei Radiation mechanisms: non-thermal Radiation mechanisms: thermal Black hole physics |
description |
With the aim of better understanding the physical processes that produce the continuous emission in active galactic nuclei (AGNs), a snapshot of the overall continuous energy distribution of NGC 3783, from γ-ray to radio wavelengths, has been obtained within the framework of the World Astronomy Days. The data collected in this campaign are from GRO, ROSAT, Voyager 2, IUE, HST, ESO, CTIO, SAAO and the VLA. Great care has been taken in disentangling the genuine AGN continuous emission from other contributions: depending on the waveband, the latter might be (i) unrelated contaminating sources in cases where the instrument field of view is large, (ii) components within which the AGN is embedded, such as the stellar bulge population which accounts for a significant fraction of the optical continuum, and free-bound and FeII blends which contribute to the ultraviolet flux. After correction for these other contributions, the continuous emission of the isolated AGN appears to be rather ftat (i.e., approximately equal energy per unit logarithmic frequency) from soft γ-ray to infrared wavelengths. At high energies (0.1 MeV to 0.1 keV), the AGN continuum can be fitted by a power law Fv ∝ v-α with a spectral index α ≈ 1. At longer wavelengths, two excesses above this power law ("bumps") appear: in the ultraviolet, the classical big blue bump, which can be interpreted as thermal emission from the accretion disc surrounding a massive black hoJe, and in the infrared a second bump which can be ascribed to thermal emission from dust in the vicinity of the AGN, heated by ultraviolet radiation from the central source. By fitting accretion-disc models to the observed AGN spectral energy distribution, we find values for the accretion disc innermost temperature, accretion rate, and black hole mass, with some differences that depend on whether or not we extrapolate the high-energy power law up to infrared wavelengths. A fit to the IR bump above the extended a = 1 power law suggests the presence of a dust component covering the region from a distance r ≈ 80 light days (hot grains at a temperature T ≈ 1500 K) to r ≈ 60 light years (cool grains at T ≈ 200 K). The total mass of dust is around 60 Mʘ. |
publishDate |
1995 |
dc.date.issued.fl_str_mv |
1995 |
dc.date.accessioned.fl_str_mv |
2014-07-18T02:04:39Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/98097 |
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0004-6361 |
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000263014 |
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0004-6361 000263014 |
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http://hdl.handle.net/10183/98097 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Astronomy and Astrophysics. Berlin. Vol. 293, no. 2 (Jan. 1995), p. 293-308 |
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info:eu-repo/semantics/openAccess |
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openAccess |
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