Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions
Current reverberation mapping (RM) studies primarily focus on single emission lines, particularly the H β line, which may not fully reveal the geometry and kinematic properties of the broad-line region (BLR). To overcome this limitation, we have conducted multiline RM observations on two highly vari...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9c71 |
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| author | Hai-Cheng Feng Sha-Sha Li J. M. Bai H. T. Liu Kai-Xing Lu Yu-Xuan Pang Mouyuan Sun Jian-Guo Wang Yerong Xu Yang-Wei Zhang Shuying Zhou |
| author_facet | Hai-Cheng Feng Sha-Sha Li J. M. Bai H. T. Liu Kai-Xing Lu Yu-Xuan Pang Mouyuan Sun Jian-Guo Wang Yerong Xu Yang-Wei Zhang Shuying Zhou |
| author_sort | Hai-Cheng Feng |
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| description | Current reverberation mapping (RM) studies primarily focus on single emission lines, particularly the H β line, which may not fully reveal the geometry and kinematic properties of the broad-line region (BLR). To overcome this limitation, we have conducted multiline RM observations on two highly variable active galactic nuclei (AGNs), KUG 1141+371 and UGC 3374, using the Lijiang 2.4 m telescope. Our goal was to investigate the detailed structures of different regions within the BLR. We measured the time lags of multiple broad emission lines (H α , H β , H γ , He i , and He ii ) and found clear evidence of radial ionization stratification in the BLRs of both AGNs. Velocity-resolved RM analysis revealed distinct geometry and kinematics between the inner and outer regions of the BLRs. Assuming that the velocity-resolved lags reflect the kinematics of the BLR, our observations indicate that: (1) in KUG 1141+371, the inner BLR exhibits outflow signatures, while the outer region is consistent with virialized motion; and (2) in UGC 3374, the inner region displays virial motion, while the outer region shows inflow. Furthermore, we detected “breathing” behavior in the outer BLR regions of both AGNs, while the inner BLR regions show “anti-breathing,” which may be linked to intrinsic BLR properties. We discuss these findings in the context of various BLR formation models, highlighting the importance of long-term, multiline RM campaigns in understanding of BLR structure and evolution. Additionally, our results suggest that the observed stratification in BLR geometry and kinematics may contribute to the scatter in black hole mass estimates and the rapid changes in velocity-resolved RM signatures reported in recent studies. |
| format | Article |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-1aa77a1ff8f544f1b506b9fa48c6d5102025-01-22T08:36:31ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979213110.3847/1538-4357/ad9c71Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line RegionsHai-Cheng Feng0https://orcid.org/0000-0002-1530-2680Sha-Sha Li1https://orcid.org/0000-0003-3823-3419J. M. Bai2H. T. Liu3https://orcid.org/0000-0002-2153-3688Kai-Xing Lu4https://orcid.org/0000-0002-2310-0982Yu-Xuan Pang5https://orcid.org/0009-0005-3823-9302Mouyuan Sun6https://orcid.org/0000-0002-0771-2153Jian-Guo Wang7https://orcid.org/0000-0003-4156-3793Yerong Xu8https://orcid.org/0000-0002-2523-5485Yang-Wei Zhang9https://orcid.org/0009-0000-7791-8192Shuying Zhou10https://orcid.org/0009-0005-2801-6594Yunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of China; Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of China; Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of China; Key Laboratory of Radio Astronomy and Technology, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of ChinaDepartment of Astronomy, School of Physics, Peking University , Beijing 100871, People’s Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University , Beijing 100871, People’s Republic of ChinaDepartment of Astronomy, Xiamen University , Xiamen, Fujian 361005, People’s Republic of ChinaYunnan Observatories, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China ; hcfeng@ynao.ac.cn, lishasha@ynao.ac.cn; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, Yunnan, People’s Republic of China; Center for Astronomical Mega-Science, Chinese Academy of Sciences , 20A Datun Road, Chaoyang District, Beijing 100012, People’s Republic of ChinaINAF—IASF Palermo , Via U. La Malfa 153, I-90146 Palermo, Italy; Department of Astronomy & Physics, Saint Mary’s University , 923 Robie Street, Halifax, NS B3H 3C3, CanadaSouth-Western Institute for Astronomy Research, Yunnan University , Kunming 650500, People’s Republic of ChinaDepartment of Astronomy, Xiamen University , Xiamen, Fujian 361005, People’s Republic of ChinaCurrent reverberation mapping (RM) studies primarily focus on single emission lines, particularly the H β line, which may not fully reveal the geometry and kinematic properties of the broad-line region (BLR). To overcome this limitation, we have conducted multiline RM observations on two highly variable active galactic nuclei (AGNs), KUG 1141+371 and UGC 3374, using the Lijiang 2.4 m telescope. Our goal was to investigate the detailed structures of different regions within the BLR. We measured the time lags of multiple broad emission lines (H α , H β , H γ , He i , and He ii ) and found clear evidence of radial ionization stratification in the BLRs of both AGNs. Velocity-resolved RM analysis revealed distinct geometry and kinematics between the inner and outer regions of the BLRs. Assuming that the velocity-resolved lags reflect the kinematics of the BLR, our observations indicate that: (1) in KUG 1141+371, the inner BLR exhibits outflow signatures, while the outer region is consistent with virialized motion; and (2) in UGC 3374, the inner region displays virial motion, while the outer region shows inflow. Furthermore, we detected “breathing” behavior in the outer BLR regions of both AGNs, while the inner BLR regions show “anti-breathing,” which may be linked to intrinsic BLR properties. We discuss these findings in the context of various BLR formation models, highlighting the importance of long-term, multiline RM campaigns in understanding of BLR structure and evolution. Additionally, our results suggest that the observed stratification in BLR geometry and kinematics may contribute to the scatter in black hole mass estimates and the rapid changes in velocity-resolved RM signatures reported in recent studies.https://doi.org/10.3847/1538-4357/ad9c71Active galactic nucleiSeyfert galaxiesTime domain astronomyReverberation mappingSupermassive black holes |
| spellingShingle | Hai-Cheng Feng Sha-Sha Li J. M. Bai H. T. Liu Kai-Xing Lu Yu-Xuan Pang Mouyuan Sun Jian-Guo Wang Yerong Xu Yang-Wei Zhang Shuying Zhou Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions The Astrophysical Journal Active galactic nuclei Seyfert galaxies Time domain astronomy Reverberation mapping Supermassive black holes |
| title | Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions |
| title_full | Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions |
| title_fullStr | Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions |
| title_full_unstemmed | Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions |
| title_short | Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions |
| title_sort | reverberation mapping of two variable active galactic nuclei probing the distinct characteristics of the inner and outer broad line regions |
| topic | Active galactic nuclei Seyfert galaxies Time domain astronomy Reverberation mapping Supermassive black holes |
| url | https://doi.org/10.3847/1538-4357/ad9c71 |
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