Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915357067837440 |
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| author | Liu, Jun-Rong Wang, Jian-Min Collaboration, Fermi-LAT |
| author_facet | Liu, Jun-Rong Wang, Jian-Min Collaboration, Fermi-LAT |
| contents | Relativistic jets around supermassive black holes (SMBHs) are well-known powerful $γ$-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in $γ$-ray bands is still unknown despite of great observational efforts made in the last 3 decades. Considering the previous efforts, we carefully select an AGN sample composed of 37 nearby Seyfert galaxies with ultra-hard X-rays for the goals of $γ$-ray detections by excluding all potential contamination in this band. Adopting a stacking technique, here we report the significant $γ$-ray detection (${\rm TS}=30.6$, or $5.2\,σ$) from the sample using 15-year Fermi-Large Area Telescope (LAT) observation. We find an average $γ$-ray luminosity of the sample as $(1.5\pm1.0)\times10^{40}{\,\rm erg\,s^{-1}}$ at energies from 1-300\,GeV. Limited by the well-known pair production from the interaction of $γ$-rays with low energy photons, $\gtrsim$ several GeV $γ$-rays are found to originate from an extended corona ($\sim 2.7\times 10^6\,R_{\rm g}$), whereas the canonical much more compact X-ray corona ($\sim 10\,R_{\rm g}$) is responsible for 1 to several GeV $γ$-rays. The finding of the compact region lends to strong supports to the long-time theoretical expectations, but the extended corona is beyond all the existing models. One promising scenario is that the electron-positron pairs produced in the compact X-ray corona would expand as fireball, similar to that in $γ$-ray bursts, forming the structure of extended corona. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_19189 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei Liu, Jun-Rong Wang, Jian-Min Collaboration, Fermi-LAT High Energy Astrophysical Phenomena Astrophysics of Galaxies Relativistic jets around supermassive black holes (SMBHs) are well-known powerful $γ$-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in $γ$-ray bands is still unknown despite of great observational efforts made in the last 3 decades. Considering the previous efforts, we carefully select an AGN sample composed of 37 nearby Seyfert galaxies with ultra-hard X-rays for the goals of $γ$-ray detections by excluding all potential contamination in this band. Adopting a stacking technique, here we report the significant $γ$-ray detection (${\rm TS}=30.6$, or $5.2\,σ$) from the sample using 15-year Fermi-Large Area Telescope (LAT) observation. We find an average $γ$-ray luminosity of the sample as $(1.5\pm1.0)\times10^{40}{\,\rm erg\,s^{-1}}$ at energies from 1-300\,GeV. Limited by the well-known pair production from the interaction of $γ$-rays with low energy photons, $\gtrsim$ several GeV $γ$-rays are found to originate from an extended corona ($\sim 2.7\times 10^6\,R_{\rm g}$), whereas the canonical much more compact X-ray corona ($\sim 10\,R_{\rm g}$) is responsible for 1 to several GeV $γ$-rays. The finding of the compact region lends to strong supports to the long-time theoretical expectations, but the extended corona is beyond all the existing models. One promising scenario is that the electron-positron pairs produced in the compact X-ray corona would expand as fireball, similar to that in $γ$-ray bursts, forming the structure of extended corona. |
| title | Fermi detection of gamma-ray Emission from the Hot Coronae of Radio-quiet Active Galactic Nuclei |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2502.19189 |