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| Format: | Preprint |
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2025
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| Online-Zugang: | https://arxiv.org/abs/2511.02186 |
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| _version_ | 1866908626556289024 |
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| author | Yanagisawa, Kazuki Oka, Tomoharu Ariyama, Ryo Yanagihara, Kazuki iwata, Yuhei Takahashi, Mikiya M. |
| author_facet | Yanagisawa, Kazuki Oka, Tomoharu Ariyama, Ryo Yanagihara, Kazuki iwata, Yuhei Takahashi, Mikiya M. |
| contents | We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array (ALMA) archival data to investigate flux variability in Sagittarius A$^*$ (Sgr A$^*$), the supermassive black hole at the Galactic Center. Among these, we identified a rare but unusually clear and coherent ~52-minute sinusoidal modulation at 230 GHz, with a statistical significance exceeding 5σ. Modeling with a Doppler-boosted hotspot scenario yields an orbital radius of ~4 Schwarzschild radii and a disk inclination of 8$^\circ$ (or 172$^\circ$), providing the first direct millimeter wavelength constraint on the inner accretion flow geometry. This nearly face-on inclination is in good agreement with previous constraints from GRAVITY and EHT observations. These findings provide robust, independent evidence that millimeter-wave periodicity can directly probe the innermost accretion flow geometry, offering a powerful complement to variability studies at infrared and X-ray wavelengths. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_02186 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A Face-on Accretion Disk Geometry Revealed by Millimeter-wave Periodicity in Sgr A$^*$ Yanagisawa, Kazuki Oka, Tomoharu Ariyama, Ryo Yanagihara, Kazuki iwata, Yuhei Takahashi, Mikiya M. High Energy Astrophysical Phenomena Astrophysics of Galaxies We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array (ALMA) archival data to investigate flux variability in Sagittarius A$^*$ (Sgr A$^*$), the supermassive black hole at the Galactic Center. Among these, we identified a rare but unusually clear and coherent ~52-minute sinusoidal modulation at 230 GHz, with a statistical significance exceeding 5σ. Modeling with a Doppler-boosted hotspot scenario yields an orbital radius of ~4 Schwarzschild radii and a disk inclination of 8$^\circ$ (or 172$^\circ$), providing the first direct millimeter wavelength constraint on the inner accretion flow geometry. This nearly face-on inclination is in good agreement with previous constraints from GRAVITY and EHT observations. These findings provide robust, independent evidence that millimeter-wave periodicity can directly probe the innermost accretion flow geometry, offering a powerful complement to variability studies at infrared and X-ray wavelengths. |
| title | A Face-on Accretion Disk Geometry Revealed by Millimeter-wave Periodicity in Sgr A$^*$ |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2511.02186 |