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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.07482 |
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| _version_ | 1866913935819538432 |
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| author | Bai, Zhaoyu Cardoso, Vitor Chen, Yifan Do, Tuan Hees, Aurélien Xiao, Huangyu Xue, Xiao |
| author_facet | Bai, Zhaoyu Cardoso, Vitor Chen, Yifan Do, Tuan Hees, Aurélien Xiao, Huangyu Xue, Xiao |
| contents | Axions, encompassing both QCD axions and axion-like particles, can generate loop-induced quadratic couplings to electromagnetic field strength tensors, resulting in oscillatory shifts of the fine-structure constant. Near a Kerr black hole, an axion field with a Compton wavelength comparable to the event horizon can exponentially grow through the superradiance mechanism, potentially reaching a maximum amplitude near the decay constant, provided this scale is below approximately $10^{16}$ GeV. The saturated axion cloud formed around the black hole induces characteristic oscillations in the fine-structure constant, with a period of $10$-$40$ minutes determined by the axion mass, and a spatial profile governed by the axion wavefunction and its coupling strength. At lower axion masses, axion dark matter can form a soliton-like core characterized by a nearly constant amplitude, extending measurable variations of the fine-structure constant to greater distances. Precise spectroscopic measurements of S-stars orbiting the supermassive black hole Sgr A$^*$ provide a powerful probe of these predictions, potentially excluding substantial regions of parameter space for quadratic scalar couplings to photons, owing to the high boson density near the Galactic Center. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_07482 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Probing Axions via Spectroscopic Measurements of S-stars at the Galactic Center Bai, Zhaoyu Cardoso, Vitor Chen, Yifan Do, Tuan Hees, Aurélien Xiao, Huangyu Xue, Xiao High Energy Physics - Phenomenology High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology Axions, encompassing both QCD axions and axion-like particles, can generate loop-induced quadratic couplings to electromagnetic field strength tensors, resulting in oscillatory shifts of the fine-structure constant. Near a Kerr black hole, an axion field with a Compton wavelength comparable to the event horizon can exponentially grow through the superradiance mechanism, potentially reaching a maximum amplitude near the decay constant, provided this scale is below approximately $10^{16}$ GeV. The saturated axion cloud formed around the black hole induces characteristic oscillations in the fine-structure constant, with a period of $10$-$40$ minutes determined by the axion mass, and a spatial profile governed by the axion wavefunction and its coupling strength. At lower axion masses, axion dark matter can form a soliton-like core characterized by a nearly constant amplitude, extending measurable variations of the fine-structure constant to greater distances. Precise spectroscopic measurements of S-stars orbiting the supermassive black hole Sgr A$^*$ provide a powerful probe of these predictions, potentially excluding substantial regions of parameter space for quadratic scalar couplings to photons, owing to the high boson density near the Galactic Center. |
| title | Probing Axions via Spectroscopic Measurements of S-stars at the Galactic Center |
| topic | High Energy Physics - Phenomenology High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2507.07482 |