Saved in:
| Main Authors: | , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2509.12978 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866915497233088512 |
|---|---|
| author | Hu, Chen-Ran Huang, Yong-Feng Cui, Lang Zhang, Hanle Li, Jiang-Tao Ji, Li Geng, Jin-Jun Amat, Orkash Xu, Fan Du, Chen Zhang, Wen-Long Zou, Ze-Cheng Dong, Xiao-Fei Deng, Chen Jiang, Pengfei Liao, Jie |
| author_facet | Hu, Chen-Ran Huang, Yong-Feng Cui, Lang Zhang, Hanle Li, Jiang-Tao Ji, Li Geng, Jin-Jun Amat, Orkash Xu, Fan Du, Chen Zhang, Wen-Long Zou, Ze-Cheng Dong, Xiao-Fei Deng, Chen Jiang, Pengfei Liao, Jie |
| contents | We present a systematic analysis on the X-ray variability in 13 bright quasars at z > 4.5, combining recent Swift observations from 2021 to 2023 and archival multi-epoch observations. Upper limits of the luminosity measurements were included in the analysis by using the Kaplan-Meier estimator method. It is found that the high-z quasars exhibit X-ray variability on both short-term (hours-to-days) and intermediate-term (weeks-to-months) timescales, with short-term variability dominating the overall variation. A linear correlation exists between the global mean ($μ_{\mathrm{L_{2-10\,keV}}}$) and standard deviation ($σ_{\mathrm{L_{2-10\,keV}}}$) of X-ray luminosities, which is independent of the X-ray photon index and optical-to-X-ray spectral slope. The localized stochastic magnetic reconnection mechanism is strongly favored, which can naturally lead to a scale-invariant power-law energy distribution and satisfactorily explain the correlation. The $σ$-$μ$ correlation parallels with the well-documented rms-flux relation of low-z active galactic nuclei (AGNs), implying the magnetic reconnection mechanism could drive short-timescale X-ray variability in both high- and low-z AGNs. The highest-z quasar in our sample, J142952+544717 (z = 6.18), shows a luminosity distribution extending to ${10}^{47}\ \rm{erg\ {s}^{-1}}$ with a not conspicuous median luminosity. On the other hand, J143023+420436 (z = 4.7), which hosts the most relativistic jet among known high-z blazars, is dominated in the high-luminosity regime (${10}^{47}\ \rm{erg\ {s}^{-1}}$ ), making it an ideal target for multi-wavelength follow-up observations. J090630+693030 is found to have a rest-frame period of 182.46 days and J143023+420436 has a period of 16.89 days, both could be explained by the global evolution of plasmoid chains, in which magnetic islands formed during reconnection may merge successively. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_12978 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Magnetic Reconnection as a Potential Driver of X-ray Variability in Active Galactic Nuclei Hu, Chen-Ran Huang, Yong-Feng Cui, Lang Zhang, Hanle Li, Jiang-Tao Ji, Li Geng, Jin-Jun Amat, Orkash Xu, Fan Du, Chen Zhang, Wen-Long Zou, Ze-Cheng Dong, Xiao-Fei Deng, Chen Jiang, Pengfei Liao, Jie High Energy Astrophysical Phenomena We present a systematic analysis on the X-ray variability in 13 bright quasars at z > 4.5, combining recent Swift observations from 2021 to 2023 and archival multi-epoch observations. Upper limits of the luminosity measurements were included in the analysis by using the Kaplan-Meier estimator method. It is found that the high-z quasars exhibit X-ray variability on both short-term (hours-to-days) and intermediate-term (weeks-to-months) timescales, with short-term variability dominating the overall variation. A linear correlation exists between the global mean ($μ_{\mathrm{L_{2-10\,keV}}}$) and standard deviation ($σ_{\mathrm{L_{2-10\,keV}}}$) of X-ray luminosities, which is independent of the X-ray photon index and optical-to-X-ray spectral slope. The localized stochastic magnetic reconnection mechanism is strongly favored, which can naturally lead to a scale-invariant power-law energy distribution and satisfactorily explain the correlation. The $σ$-$μ$ correlation parallels with the well-documented rms-flux relation of low-z active galactic nuclei (AGNs), implying the magnetic reconnection mechanism could drive short-timescale X-ray variability in both high- and low-z AGNs. The highest-z quasar in our sample, J142952+544717 (z = 6.18), shows a luminosity distribution extending to ${10}^{47}\ \rm{erg\ {s}^{-1}}$ with a not conspicuous median luminosity. On the other hand, J143023+420436 (z = 4.7), which hosts the most relativistic jet among known high-z blazars, is dominated in the high-luminosity regime (${10}^{47}\ \rm{erg\ {s}^{-1}}$ ), making it an ideal target for multi-wavelength follow-up observations. J090630+693030 is found to have a rest-frame period of 182.46 days and J143023+420436 has a period of 16.89 days, both could be explained by the global evolution of plasmoid chains, in which magnetic islands formed during reconnection may merge successively. |
| title | Magnetic Reconnection as a Potential Driver of X-ray Variability in Active Galactic Nuclei |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2509.12978 |