The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548
Autor(a) principal: | |
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Data de Publicação: | 2019 |
Outros Autores: | , , , , , , , , , , , , , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/203881 |
Resumo: | We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dust response times. Here we report results from a 1 yr campaign on NGC 5548. The hot dust responds to changes in the irradiating flux with a lag time of ∼70 light-days, similar to what was previously found in photometric reverberation campaigns. The mean and rms spectra are similar, implying that the same dust component dominates both the emission and the variations. The dust lag time is consistent with the luminosity-based dust radius only if we assume a wavelength-independent dust emissivity law, i.e. a blackbody, which is appropriate for grains of large sizes (of a few μm). For such grains the dust temperature is ∼1450 K. Therefore, silicate grains have most likely evaporated and carbon is the main chemical component. But the hot dust is not close to its sublimation temperature, contrary to popular belief. This is further supported by our observation of temperature variations largely consistent with a heating/cooling process. Therefore, the inner dust-free region is enlarged and the dusty torus rather a ‘dusty wall’, whose inner radius is expected to be luminosity-invariant. The dust-destruction mechanism that enlarges the dust-free region seems to also partly affect the dusty region. We observe a cyclical decrease in dust mass with implied dust reformation times of ∼5–6 months |
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Landt, HermineWard, Martin JohnKynoch, DanielPackham, ChristopherFerland, Gary J.Lawrence, AndyPott, Jörg-UweEsser, JohannesHorne, KeithStarkey, David A.Malhotra, DeepakFausnaugh, MichaelPeterson, Bradley M.Wilman, Richard J.Riffel, Rogemar AndréStorchi-Bergmann, ThaisaBarth, Aaron J.Villforth, CarolinWinkler, Hartmut2019-12-27T04:04:50Z20190035-8711http://hdl.handle.net/10183/203881001105696We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dust response times. Here we report results from a 1 yr campaign on NGC 5548. The hot dust responds to changes in the irradiating flux with a lag time of ∼70 light-days, similar to what was previously found in photometric reverberation campaigns. The mean and rms spectra are similar, implying that the same dust component dominates both the emission and the variations. The dust lag time is consistent with the luminosity-based dust radius only if we assume a wavelength-independent dust emissivity law, i.e. a blackbody, which is appropriate for grains of large sizes (of a few μm). For such grains the dust temperature is ∼1450 K. Therefore, silicate grains have most likely evaporated and carbon is the main chemical component. But the hot dust is not close to its sublimation temperature, contrary to popular belief. This is further supported by our observation of temperature variations largely consistent with a heating/cooling process. Therefore, the inner dust-free region is enlarged and the dusty torus rather a ‘dusty wall’, whose inner radius is expected to be luminosity-invariant. The dust-destruction mechanism that enlarges the dust-free region seems to also partly affect the dusty region. We observe a cyclical decrease in dust mass with implied dust reformation times of ∼5–6 monthsapplication/pdfengMonthly notices of the royal astronomical society. Oxford. Vol. 489, no. 2 (Oct. 2019), p. 1572-1589Galaxias seyfertGaláxia NGC 5548Astronomia infravermelhaQuasarsGalaxies: SeyfertQuasars: emission linesQuasars: individual: NGC 5548infrared: galaxiesThe first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548Estrangeiroinfo: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:UFRGSTEXT001105696.pdf.txt001105696.pdf.txtExtracted Texttext/plain109094http://www.lume.ufrgs.br/bitstream/10183/203881/2/001105696.pdf.txt819a2dba60706758284c926f59a3344dMD52ORIGINAL001105696.pdfTexto completo (inglês)application/pdf1432289http://www.lume.ufrgs.br/bitstream/10183/203881/1/001105696.pdfb519fd7ed4421efdb63a1f4bbf88c0a6MD5110183/2038812019-12-28 05:03:54.665613oai:www.lume.ufrgs.br:10183/203881Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2019-12-28T07:03:54Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
title |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
spellingShingle |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 Landt, Hermine Galaxias seyfert Galáxia NGC 5548 Astronomia infravermelha Quasars Galaxies: Seyfert Quasars: emission lines Quasars: individual: NGC 5548 infrared: galaxies |
title_short |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
title_full |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
title_fullStr |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
title_full_unstemmed |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
title_sort |
The first spectroscopic dust reverberation programme on active galactic nuclei : the torus in NGC 5548 |
author |
Landt, Hermine |
author_facet |
Landt, Hermine Ward, Martin John Kynoch, Daniel Packham, Christopher Ferland, Gary J. Lawrence, Andy Pott, Jörg-Uwe Esser, Johannes Horne, Keith Starkey, David A. Malhotra, Deepak Fausnaugh, Michael Peterson, Bradley M. Wilman, Richard J. Riffel, Rogemar André Storchi-Bergmann, Thaisa Barth, Aaron J. Villforth, Carolin Winkler, Hartmut |
author_role |
author |
author2 |
Ward, Martin John Kynoch, Daniel Packham, Christopher Ferland, Gary J. Lawrence, Andy Pott, Jörg-Uwe Esser, Johannes Horne, Keith Starkey, David A. Malhotra, Deepak Fausnaugh, Michael Peterson, Bradley M. Wilman, Richard J. Riffel, Rogemar André Storchi-Bergmann, Thaisa Barth, Aaron J. Villforth, Carolin Winkler, Hartmut |
author2_role |
author author author author author author author author author author author author author author author author author author |
dc.contributor.author.fl_str_mv |
Landt, Hermine Ward, Martin John Kynoch, Daniel Packham, Christopher Ferland, Gary J. Lawrence, Andy Pott, Jörg-Uwe Esser, Johannes Horne, Keith Starkey, David A. Malhotra, Deepak Fausnaugh, Michael Peterson, Bradley M. Wilman, Richard J. Riffel, Rogemar André Storchi-Bergmann, Thaisa Barth, Aaron J. Villforth, Carolin Winkler, Hartmut |
dc.subject.por.fl_str_mv |
Galaxias seyfert Galáxia NGC 5548 Astronomia infravermelha Quasars |
topic |
Galaxias seyfert Galáxia NGC 5548 Astronomia infravermelha Quasars Galaxies: Seyfert Quasars: emission lines Quasars: individual: NGC 5548 infrared: galaxies |
dc.subject.eng.fl_str_mv |
Galaxies: Seyfert Quasars: emission lines Quasars: individual: NGC 5548 infrared: galaxies |
description |
We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dust response times. Here we report results from a 1 yr campaign on NGC 5548. The hot dust responds to changes in the irradiating flux with a lag time of ∼70 light-days, similar to what was previously found in photometric reverberation campaigns. The mean and rms spectra are similar, implying that the same dust component dominates both the emission and the variations. The dust lag time is consistent with the luminosity-based dust radius only if we assume a wavelength-independent dust emissivity law, i.e. a blackbody, which is appropriate for grains of large sizes (of a few μm). For such grains the dust temperature is ∼1450 K. Therefore, silicate grains have most likely evaporated and carbon is the main chemical component. But the hot dust is not close to its sublimation temperature, contrary to popular belief. This is further supported by our observation of temperature variations largely consistent with a heating/cooling process. Therefore, the inner dust-free region is enlarged and the dusty torus rather a ‘dusty wall’, whose inner radius is expected to be luminosity-invariant. The dust-destruction mechanism that enlarges the dust-free region seems to also partly affect the dusty region. We observe a cyclical decrease in dust mass with implied dust reformation times of ∼5–6 months |
publishDate |
2019 |
dc.date.accessioned.fl_str_mv |
2019-12-27T04:04:50Z |
dc.date.issued.fl_str_mv |
2019 |
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/10183/203881 |
dc.identifier.issn.pt_BR.fl_str_mv |
0035-8711 |
dc.identifier.nrb.pt_BR.fl_str_mv |
001105696 |
identifier_str_mv |
0035-8711 001105696 |
url |
http://hdl.handle.net/10183/203881 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Monthly notices of the royal astronomical society. Oxford. Vol. 489, no. 2 (Oct. 2019), p. 1572-1589 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
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application/pdf |
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