Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT
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| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| author | Kaur, K. Rammala-Zitha, I. Basu, A. Witzel, G. Wielgus, M. Balakrishnan, V. Barr, E. D. Brunthaler, A. Buchner, S. Champion, D. J. Hoeft, M. Khan, S. Klöckner, H. -R. König, C. Kramer, M. Krishnan, V. Venkatraman Ma, Y. K. Mao, S. A. Padmanabh, P. V. Ranchod, S. Sridhar, S. S. Wagenveld, J. D. Wharton, R. S. Wucknitz, O. |
| author_facet | Kaur, K. Rammala-Zitha, I. Basu, A. Witzel, G. Wielgus, M. Balakrishnan, V. Barr, E. D. Brunthaler, A. Buchner, S. Champion, D. J. Hoeft, M. Khan, S. Klöckner, H. -R. König, C. Kramer, M. Krishnan, V. Venkatraman Ma, Y. K. Mao, S. A. Padmanabh, P. V. Ranchod, S. Sridhar, S. S. Wagenveld, J. D. Wharton, R. S. Wucknitz, O. |
| contents | The supermassive black hole Sagittarius A* (Sgr A*) exhibits temporal and spectral variability across the electromagnetic spectrum. However, variability at radio frequencies below ~ 5 GHz for timescales shorter than a day remains largely unexplored. We investigate the variability of Sgr A* at 2.79 GHz on short timescales (1 min), to probe an under-explored regime of its emission process. Through point-source model fitting in the uv-domain, we analyse the flux density variation of Sgr A* over an 8 h observation. We detect flux variation on a few tens of minute timescale with a modulation index of 6.11 %, a mean flux density of ($827 \pm 0.1_{\mathrm{stat}} \pm 33_{\mathrm{sys}}) \, \mathrm{mJy}$, and a mean spectral slope of $0.08\pm0.03$. Furthermore, we measure the slope of the structure function of the observed light curve as $0.81 \pm 0.05$ with a characteristic timescale of about 120 min. Our study at low radio frequencies is a critical step toward constraining the physical mechanisms that drive Sgr A*'s variable emission and its spectral energy distribution. Our study suggests that variability at centimetre and millimetre wavelengths is likely more closely related than previously thought. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_22638 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT Kaur, K. Rammala-Zitha, I. Basu, A. Witzel, G. Wielgus, M. Balakrishnan, V. Barr, E. D. Brunthaler, A. Buchner, S. Champion, D. J. Hoeft, M. Khan, S. Klöckner, H. -R. König, C. Kramer, M. Krishnan, V. Venkatraman Ma, Y. K. Mao, S. A. Padmanabh, P. V. Ranchod, S. Sridhar, S. S. Wagenveld, J. D. Wharton, R. S. Wucknitz, O. Astrophysics of Galaxies High Energy Astrophysical Phenomena The supermassive black hole Sagittarius A* (Sgr A*) exhibits temporal and spectral variability across the electromagnetic spectrum. However, variability at radio frequencies below ~ 5 GHz for timescales shorter than a day remains largely unexplored. We investigate the variability of Sgr A* at 2.79 GHz on short timescales (1 min), to probe an under-explored regime of its emission process. Through point-source model fitting in the uv-domain, we analyse the flux density variation of Sgr A* over an 8 h observation. We detect flux variation on a few tens of minute timescale with a modulation index of 6.11 %, a mean flux density of ($827 \pm 0.1_{\mathrm{stat}} \pm 33_{\mathrm{sys}}) \, \mathrm{mJy}$, and a mean spectral slope of $0.08\pm0.03$. Furthermore, we measure the slope of the structure function of the observed light curve as $0.81 \pm 0.05$ with a characteristic timescale of about 120 min. Our study at low radio frequencies is a critical step toward constraining the physical mechanisms that drive Sgr A*'s variable emission and its spectral energy distribution. Our study suggests that variability at centimetre and millimetre wavelengths is likely more closely related than previously thought. |
| title | Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT |
| topic | Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2604.22638 |