The X-ray/UV Connection in NGC 5548: A Rapidly Varying Corona
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arXiv
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| Autores principales: | , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866914283926847488 |
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| author | Papoutsis, M. Papadakis, I. E. Panagiotou, C. Kammoun, E. Dovciak, M. |
| author_facet | Papoutsis, M. Papadakis, I. E. Panagiotou, C. Kammoun, E. Dovciak, M. |
| contents | Recent intensive monitoring campaigns of active galactic nuclei (AGN) have provided simultaneous X-ray, UV, and optical data of unprecedented quality. The observations reveal a strong correlation between the UV and optical variability, but a weaker correlation between the X-ray and UV bands, challenging the standard X-ray reprocessing scenario. We revisit the X-ray/UV connection in NGC 5548 by fitting archival 2014 HST and Swift/XRT light curves assuming X-ray reverberation from a dynamically evolving X-ray corona. Our results show that, as long as the corona height, photon index and power vary over time, X-ray reverberation can explain the observed UV and optical variability within 2% and 5%, respectively (on average). The evolution of the best-fit parameters suggests that fast changes in coronal geometry and energetics on a time scale of days are required to explain the observed variability. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_05739 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The X-ray/UV Connection in NGC 5548: A Rapidly Varying Corona Papoutsis, M. Papadakis, I. E. Panagiotou, C. Kammoun, E. Dovciak, M. High Energy Astrophysical Phenomena Astrophysics of Galaxies Recent intensive monitoring campaigns of active galactic nuclei (AGN) have provided simultaneous X-ray, UV, and optical data of unprecedented quality. The observations reveal a strong correlation between the UV and optical variability, but a weaker correlation between the X-ray and UV bands, challenging the standard X-ray reprocessing scenario. We revisit the X-ray/UV connection in NGC 5548 by fitting archival 2014 HST and Swift/XRT light curves assuming X-ray reverberation from a dynamically evolving X-ray corona. Our results show that, as long as the corona height, photon index and power vary over time, X-ray reverberation can explain the observed UV and optical variability within 2% and 5%, respectively (on average). The evolution of the best-fit parameters suggests that fast changes in coronal geometry and energetics on a time scale of days are required to explain the observed variability. |
| title | The X-ray/UV Connection in NGC 5548: A Rapidly Varying Corona |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.05739 |