Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus
“Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years. However, it is still unclear whether materials in broad-line regions (BLRs) in CLAGNs appear and disappe...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/aca963 |
| _version_ | 1797701298677612544 |
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| author | Hirofumi Noda Taisei Mineta Takeo Minezaki Hiroaki Sameshima Mitsuru Kokubo Taiki Kawamuro Satoshi Yamada Takashi Horiuchi Hironori Matsumoto Makoto Watanabe Kumiko Morihana Yoichi Itoh Koji S. Kawabata Yasushi Fukazawa |
| author_facet | Hirofumi Noda Taisei Mineta Takeo Minezaki Hiroaki Sameshima Mitsuru Kokubo Taiki Kawamuro Satoshi Yamada Takashi Horiuchi Hironori Matsumoto Makoto Watanabe Kumiko Morihana Yoichi Itoh Koji S. Kawabata Yasushi Fukazawa |
| author_sort | Hirofumi Noda |
| collection | DOAJ |
| description | “Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years. However, it is still unclear whether materials in broad-line regions (BLRs) in CLAGNs appear and disappear during the type-transition or remain at the same location while the line production is simply activated or deactivated. Here we present our X-ray–optical monitoring results of a CLAGN, NGC 3516, by Suzaku, Swift, and ground telescopes, with our primary focus on the narrow Fe–K α emission line, which is an effective probe of the BLR materials. We detected significant variations of the narrow Fe–K α line on a timescale of tens of days during the type-2 (faint) phase in 2013–2014, and conducted “narrow Fe–K α reverberation mapping,” comparing its flux variation with those of the X-ray continuum from a corona and B -band continuum from an accretion disk. We derived, as a result, a time lag of ${10.1}_{-5.6}^{+5.8}$ days (1 σ errors) for the Fe–K α line behind the continuum, which is consistent with the location of the BLR determined in optical spectroscopic reverberation mapping during the type-1 (bright) phase. This finding shows that the BLR materials remained at the same location without emitting optical broad lines during the type-2 phase. Considering the drastic decrease of the radiation during the type-transition, our result is possibly inconsistent with the hotly discussed formation models of the BLR, which propose that the radiative pressure from an accretion disk should be the main driving force. |
| first_indexed | 2024-03-12T04:34:24Z |
| format | Article |
| id | doaj.art-ffec9f2d98a14801846eb48881980fb0 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:34:24Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-ffec9f2d98a14801846eb48881980fb02023-09-03T09:58:14ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194316310.3847/1538-4357/aca963Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic NucleusHirofumi Noda0https://orcid.org/0000-0001-6020-517XTaisei Mineta1Takeo Minezaki2https://orcid.org/0000-0002-2933-048XHiroaki Sameshima3https://orcid.org/0000-0001-6401-723XMitsuru Kokubo4https://orcid.org/0000-0001-6402-1415Taiki Kawamuro5https://orcid.org/0000-0002-6808-2052Satoshi Yamada6https://orcid.org/0000-0002-9754-3081Takashi Horiuchi7https://orcid.org/0000-0001-5925-3350Hironori Matsumoto8Makoto Watanabe9https://orcid.org/0000-0002-3656-4081Kumiko Morihana10https://orcid.org/0000-0002-4895-0908Yoichi Itoh11https://orcid.org/0000-0002-3231-1159Koji S. Kawabata12https://orcid.org/0000-0001-6099-9539Yasushi Fukazawa13https://orcid.org/0000-0002-0921-8837Department of Earth and Space Science, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan noda@ess.sci.osaka-u.ac.jpDepartment of Earth and Space Science, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan noda@ess.sci.osaka-u.ac.jpInstitute of Astronomy, School of Science, the University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanInstitute of Astronomy, School of Science, the University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanDepartment of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USARIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, JapanRIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, JapanInstitute of Astronomy, School of Science, the University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan noda@ess.sci.osaka-u.ac.jpDepartment of Physics, Okayama University of Science , 1-1 Ridai-cho, Kita-ku, Okayama, Okayama 700-0005, JapanSubaru Telescope, National Astronomical Observatory of Japan , 650 North A’ohoku Place, Hilo, HI 96720, USANishi-harima Astronomical Observatory, Center for Astronomy, University of Hyogo , 407-2 Nichigaichi, Sayo-cho, Sayo, Hyogo 679-5313, JapanHiroshima Astrophysical Science Center, Hiroshima University , Higashi-Hiroshima, Hiroshima 739-8526, JapanDepartment of Physical Science, Hiroshima University , 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan“Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years. However, it is still unclear whether materials in broad-line regions (BLRs) in CLAGNs appear and disappear during the type-transition or remain at the same location while the line production is simply activated or deactivated. Here we present our X-ray–optical monitoring results of a CLAGN, NGC 3516, by Suzaku, Swift, and ground telescopes, with our primary focus on the narrow Fe–K α emission line, which is an effective probe of the BLR materials. We detected significant variations of the narrow Fe–K α line on a timescale of tens of days during the type-2 (faint) phase in 2013–2014, and conducted “narrow Fe–K α reverberation mapping,” comparing its flux variation with those of the X-ray continuum from a corona and B -band continuum from an accretion disk. We derived, as a result, a time lag of ${10.1}_{-5.6}^{+5.8}$ days (1 σ errors) for the Fe–K α line behind the continuum, which is consistent with the location of the BLR determined in optical spectroscopic reverberation mapping during the type-1 (bright) phase. This finding shows that the BLR materials remained at the same location without emitting optical broad lines during the type-2 phase. Considering the drastic decrease of the radiation during the type-transition, our result is possibly inconsistent with the hotly discussed formation models of the BLR, which propose that the radiative pressure from an accretion disk should be the main driving force.https://doi.org/10.3847/1538-4357/aca963X-ray active galactic nucleiActive galactic nucleiActive galaxies |
| spellingShingle | Hirofumi Noda Taisei Mineta Takeo Minezaki Hiroaki Sameshima Mitsuru Kokubo Taiki Kawamuro Satoshi Yamada Takashi Horiuchi Hironori Matsumoto Makoto Watanabe Kumiko Morihana Yoichi Itoh Koji S. Kawabata Yasushi Fukazawa Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus The Astrophysical Journal X-ray active galactic nuclei Active galactic nuclei Active galaxies |
| title | Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus |
| title_full | Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus |
| title_fullStr | Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus |
| title_full_unstemmed | Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus |
| title_short | Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus |
| title_sort | narrow fe kα reverberation mapping unveils the deactivated broad line region in a changing look active galactic nucleus |
| topic | X-ray active galactic nuclei Active galactic nuclei Active galaxies |
| url | https://doi.org/10.3847/1538-4357/aca963 |
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