On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability
Double-peaked [O iii ] profiles could potentially indicate kiloparsec-scale dual active galactic nuclei (AGNs). We analyze long-term optical light curves of 35 type 1 AGNs with such features from our recent catalog in Zheng et al. These light curves are obtained from the Catalina Sky Survey and mode...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/adf738 |
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| author | Qi Zheng Xingyu Zhu Xueguang Zhang Qirong Yuan |
| author_facet | Qi Zheng Xingyu Zhu Xueguang Zhang Qirong Yuan |
| author_sort | Qi Zheng |
| collection | DOAJ |
| description | Double-peaked [O iii ] profiles could potentially indicate kiloparsec-scale dual active galactic nuclei (AGNs). We analyze long-term optical light curves of 35 type 1 AGNs with such features from our recent catalog in Zheng et al. These light curves are obtained from the Catalina Sky Survey and modeled using a damped random walk process. A control sample of 210 normal type 1 AGNs, matched in redshift, intrinsic luminosity, and black hole mass, is also studied. If the double-peaked [O iii ] is caused by two type 1 AGNs (dual type 1 AGN), then the combined variability from the two AGNs would be expected to differ from that of a single type 1 AGN. However, there is no statistically significant difference in the variability timescale τ and intrinsic variability amplitude σ between these double-peaked AGNs and the control sample of 210 normal type 1 AGNs. Crucially, computer simulations reveal that dual AGN systems systematically produce lower variability amplitudes than single AGNs, which is inconsistent with the observed variability properties of our double-peaked [O iii ] sample. Moreover, simulations suggest that the fraction of dual type 1 AGNs is ∼3%, indicating that double-peaked [O iii ] may not be a reliable indicator of dual type 1 AGNs in these systems. However, this does not rule out the possibility that some objects may still host dual AGNs involving other combinations, such as type 1+type 2 AGNs. Future studies with larger samples and higher-quality light curves will help clarify the true nature of these systems. |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-900be15eb64b44c7b2915d8003a8c09d2025-08-22T06:19:38ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0199013310.3847/1538-4357/adf738On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical VariabilityQi Zheng0https://orcid.org/0000-0003-4583-3383Xingyu Zhu1Xueguang Zhang2https://orcid.org/0000-0001-5458-8354Qirong Yuan3https://orcid.org/0000-0002-9244-3938School of Physics and Technology, Nanjing Normal University , No. 1, Wenyuan Road, Nanjing, 210023, People’s Republic of China ; yuanqirong@njnu.edu.cnSchool of Physics and Astronomy, Beijing Normal University , Beijing, 100875, People’s Republic of ChinaGuangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, GuangXi University , No. 100, Daxue Road, Nanning, 530004, People’s Republic of China ; xgzhang@gxu.edu.cnSchool of Physics and Technology, Nanjing Normal University , No. 1, Wenyuan Road, Nanjing, 210023, People’s Republic of China ; yuanqirong@njnu.edu.cnDouble-peaked [O iii ] profiles could potentially indicate kiloparsec-scale dual active galactic nuclei (AGNs). We analyze long-term optical light curves of 35 type 1 AGNs with such features from our recent catalog in Zheng et al. These light curves are obtained from the Catalina Sky Survey and modeled using a damped random walk process. A control sample of 210 normal type 1 AGNs, matched in redshift, intrinsic luminosity, and black hole mass, is also studied. If the double-peaked [O iii ] is caused by two type 1 AGNs (dual type 1 AGN), then the combined variability from the two AGNs would be expected to differ from that of a single type 1 AGN. However, there is no statistically significant difference in the variability timescale τ and intrinsic variability amplitude σ between these double-peaked AGNs and the control sample of 210 normal type 1 AGNs. Crucially, computer simulations reveal that dual AGN systems systematically produce lower variability amplitudes than single AGNs, which is inconsistent with the observed variability properties of our double-peaked [O iii ] sample. Moreover, simulations suggest that the fraction of dual type 1 AGNs is ∼3%, indicating that double-peaked [O iii ] may not be a reliable indicator of dual type 1 AGNs in these systems. However, this does not rule out the possibility that some objects may still host dual AGNs involving other combinations, such as type 1+type 2 AGNs. Future studies with larger samples and higher-quality light curves will help clarify the true nature of these systems.https://doi.org/10.3847/1538-4357/adf738Active galactic nucleiActive galaxiesEmission line galaxiesLight curves |
| spellingShingle | Qi Zheng Xingyu Zhu Xueguang Zhang Qirong Yuan On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability The Astrophysical Journal Active galactic nuclei Active galaxies Emission line galaxies Light curves |
| title | On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability |
| title_full | On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability |
| title_fullStr | On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability |
| title_full_unstemmed | On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability |
| title_short | On Type 1 Active Galactic Nuclei with Double-peaked [O iii]. II. Properties of Long-term Optical Variability |
| title_sort | on type 1 active galactic nuclei with double peaked o iii ii properties of long term optical variability |
| topic | Active galactic nuclei Active galaxies Emission line galaxies Light curves |
| url | https://doi.org/10.3847/1538-4357/adf738 |
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