The obscuring starburst of NGC 6221 and implications for the hard x-ray background
Autor(a) principal: | |
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Data de Publicação: | 2001 |
Outros Autores: | , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/108882 |
Resumo: | We present NGC 6221 as a case study of "X-ray-loud composite galaxies", which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a power-law continuum spectrum, a broad Fe Kα line, and continuum variability on timescales of days and years. High-resolution images reveal that the detected active nucleus is relatively weak, not only at optical, but also at near-infrared wavelengths. An obscuring starburst, in which the interstellar gas and dust associated with the starburst conceal the active nucleus, accounts for these peculiar features. We demonstrate quantitatively that obscuration by column density NH=10 22 cm-² combined with relatively weak intrinsic nuclear activity can produce an optical spectrum that is characteristic of the surrounding starburst alone. While optical surveys would not identify the active nuclei that make these galaxies significant X-ray sources, such galaxies may, in fact, be important contributors to the X-ray background. |
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Levenson, Nancy A.Fernandes Junior, Roberto CidWeaver, Kim A.Heckman, Timothy M.Storchi-Bergmann, Thaisa2015-01-13T02:14:40Z20010004-637Xhttp://hdl.handle.net/10183/108882000302298We present NGC 6221 as a case study of "X-ray-loud composite galaxies", which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a power-law continuum spectrum, a broad Fe Kα line, and continuum variability on timescales of days and years. High-resolution images reveal that the detected active nucleus is relatively weak, not only at optical, but also at near-infrared wavelengths. An obscuring starburst, in which the interstellar gas and dust associated with the starburst conceal the active nucleus, accounts for these peculiar features. We demonstrate quantitatively that obscuration by column density NH=10 22 cm-² combined with relatively weak intrinsic nuclear activity can produce an optical spectrum that is characteristic of the surrounding starburst alone. While optical surveys would not identify the active nuclei that make these galaxies significant X-ray sources, such galaxies may, in fact, be important contributors to the X-ray background.application/pdfengThe astrophysical journal. Chicago. Vol. 557, no. 1, pt. 1 (Aug. 2001), p. 54-66Materia interestelarGalaxias seyfertGalaxies : individual (NGC 6221)Galaxies : SeyfertGalaxies : starburstX-rays: diuse backgroundX-rays: galaxiesThe obscuring starburst of NGC 6221 and implications for the hard x-ray backgroundEstrangeiroinfo: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:UFRGSORIGINAL000302298.pdf000302298.pdfTexto completo (inglês)application/pdf349760http://www.lume.ufrgs.br/bitstream/10183/108882/1/000302298.pdf9e80b35a4f6514700d724e33167ec39cMD51TEXT000302298.pdf.txt000302298.pdf.txtExtracted Texttext/plain65191http://www.lume.ufrgs.br/bitstream/10183/108882/2/000302298.pdf.txt2c68effa033bb87b28439cea0934448eMD52THUMBNAIL000302298.pdf.jpg000302298.pdf.jpgGenerated Thumbnailimage/jpeg2198http://www.lume.ufrgs.br/bitstream/10183/108882/3/000302298.pdf.jpgb21fe2c6382ecf2bb7f051b47e575031MD5310183/1088822018-10-23 08:38:12.686oai:www.lume.ufrgs.br:10183/108882Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2018-10-23T11:38:12Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
title |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
spellingShingle |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background Levenson, Nancy A. Materia interestelar Galaxias seyfert Galaxies : individual (NGC 6221) Galaxies : Seyfert Galaxies : starburst X-rays: diuse background X-rays: galaxies |
title_short |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
title_full |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
title_fullStr |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
title_full_unstemmed |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
title_sort |
The obscuring starburst of NGC 6221 and implications for the hard x-ray background |
author |
Levenson, Nancy A. |
author_facet |
Levenson, Nancy A. Fernandes Junior, Roberto Cid Weaver, Kim A. Heckman, Timothy M. Storchi-Bergmann, Thaisa |
author_role |
author |
author2 |
Fernandes Junior, Roberto Cid Weaver, Kim A. Heckman, Timothy M. Storchi-Bergmann, Thaisa |
author2_role |
author author author author |
dc.contributor.author.fl_str_mv |
Levenson, Nancy A. Fernandes Junior, Roberto Cid Weaver, Kim A. Heckman, Timothy M. Storchi-Bergmann, Thaisa |
dc.subject.por.fl_str_mv |
Materia interestelar Galaxias seyfert |
topic |
Materia interestelar Galaxias seyfert Galaxies : individual (NGC 6221) Galaxies : Seyfert Galaxies : starburst X-rays: diuse background X-rays: galaxies |
dc.subject.eng.fl_str_mv |
Galaxies : individual (NGC 6221) Galaxies : Seyfert Galaxies : starburst X-rays: diuse background X-rays: galaxies |
description |
We present NGC 6221 as a case study of "X-ray-loud composite galaxies", which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a power-law continuum spectrum, a broad Fe Kα line, and continuum variability on timescales of days and years. High-resolution images reveal that the detected active nucleus is relatively weak, not only at optical, but also at near-infrared wavelengths. An obscuring starburst, in which the interstellar gas and dust associated with the starburst conceal the active nucleus, accounts for these peculiar features. We demonstrate quantitatively that obscuration by column density NH=10 22 cm-² combined with relatively weak intrinsic nuclear activity can produce an optical spectrum that is characteristic of the surrounding starburst alone. While optical surveys would not identify the active nuclei that make these galaxies significant X-ray sources, such galaxies may, in fact, be important contributors to the X-ray background. |
publishDate |
2001 |
dc.date.issued.fl_str_mv |
2001 |
dc.date.accessioned.fl_str_mv |
2015-01-13T02:14:40Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
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article |
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http://hdl.handle.net/10183/108882 |
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0004-637X |
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000302298 |
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0004-637X 000302298 |
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http://hdl.handle.net/10183/108882 |
dc.language.iso.fl_str_mv |
eng |
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eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
The astrophysical journal. Chicago. Vol. 557, no. 1, pt. 1 (Aug. 2001), p. 54-66 |
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openAccess |
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