A Sandwich Model for Changing-Look AGNs
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arXiv
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| Format: | Preprint |
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2025
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| author | Ma, Qian-Qi Gu, Wei-Min Cai, Zhen-Yi Cao, Xinwu Wang, Jun-Xian Zhang, Zhi-Xiang Sun, Mouyuan |
| author_facet | Ma, Qian-Qi Gu, Wei-Min Cai, Zhen-Yi Cao, Xinwu Wang, Jun-Xian Zhang, Zhi-Xiang Sun, Mouyuan |
| contents | The spectral variability of changing-look active galactic nuclei (CL-AGNs) occurred on timescales of years to tens of years, posing a significant challenge to the standard thin disk model. In this work, we propose a sandwich model, including an optically thick disk in the mid-plane (Disk 1) and two disks of low effective optical depth on both sides (Disk 2). These two types of disks are coupled with magnetic fields, which allow viscous torque interaction between them. As a consequence, the radial velocity of Disk 1 can increase by up to three orders of magnitude compared to the standard thin disk, leading to an equivalent decrease in the accretion timescale. Therefore, such a sandwich model can account for the rapid variability in CL-AGNs. In addition, we also discuss the influence of the magnetic pressure on Disk 2. When Disk 2 is dominated by the magnetic pressure, it resembles a "warm corona", which is responsible for the soft X-ray excess. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_17246 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Sandwich Model for Changing-Look AGNs Ma, Qian-Qi Gu, Wei-Min Cai, Zhen-Yi Cao, Xinwu Wang, Jun-Xian Zhang, Zhi-Xiang Sun, Mouyuan Astrophysics of Galaxies High Energy Astrophysical Phenomena The spectral variability of changing-look active galactic nuclei (CL-AGNs) occurred on timescales of years to tens of years, posing a significant challenge to the standard thin disk model. In this work, we propose a sandwich model, including an optically thick disk in the mid-plane (Disk 1) and two disks of low effective optical depth on both sides (Disk 2). These two types of disks are coupled with magnetic fields, which allow viscous torque interaction between them. As a consequence, the radial velocity of Disk 1 can increase by up to three orders of magnitude compared to the standard thin disk, leading to an equivalent decrease in the accretion timescale. Therefore, such a sandwich model can account for the rapid variability in CL-AGNs. In addition, we also discuss the influence of the magnetic pressure on Disk 2. When Disk 2 is dominated by the magnetic pressure, it resembles a "warm corona", which is responsible for the soft X-ray excess. |
| title | A Sandwich Model for Changing-Look AGNs |
| topic | Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2504.17246 |