The Timing Evolution of the Magnetar Swift J1818.0-1607 During a Period of Reduced Activity
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Abdelmaguid, Moaz Freire, Paulo C. C. Gelfand, Joseph D. Maan, Yogesh Straal, Samayra Alford, J. A. J. |
| author_facet | Abdelmaguid, Moaz Freire, Paulo C. C. Gelfand, Joseph D. Maan, Yogesh Straal, Samayra Alford, J. A. J. |
| contents | We report results from an observational campaign of the radio-loud magnetar Swift J1818.0-1607 using the Green Bank Telescope (GBT) at 2.0 GHz, which began in November 2021 during a period of reduced activity approximately 20 months after its March 2020 outburst. Over the 60-day duration reported here, the integrated pulse profile remained consistently stable, exhibiting a single, narrow peak with with a small precursor component and no evidence of a postcursor one. This pulse profile is in sharp contrast to the double-peaked morphology observed during an observing campaign approximately 120 days preceding ours. Along with this change in the integrated pulse profile shape, we also measure a slower spin-down rate compared to the end of that preceding campaign. Together, these differences suggest that a mode-switching event likely occurred between the end of that campaign and the start of ours. Finally, we derived a phase-connected timing solution from our data, from which we inferred a characteristic age of approximately 2500 years, about 2.5 times older than the most recent published estimate, and a surface dipole magnetic field strength of roughly 1 x 10^14 G, nearly three times weaker. These updated estimates reflect the short-term variations in the magnetar's spin-down rate, from which both its age and magnetic field strength are inferred, rather than intrinsic changes in the magnetar itself. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_19698 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Timing Evolution of the Magnetar Swift J1818.0-1607 During a Period of Reduced Activity Abdelmaguid, Moaz Freire, Paulo C. C. Gelfand, Joseph D. Maan, Yogesh Straal, Samayra Alford, J. A. J. High Energy Astrophysical Phenomena We report results from an observational campaign of the radio-loud magnetar Swift J1818.0-1607 using the Green Bank Telescope (GBT) at 2.0 GHz, which began in November 2021 during a period of reduced activity approximately 20 months after its March 2020 outburst. Over the 60-day duration reported here, the integrated pulse profile remained consistently stable, exhibiting a single, narrow peak with with a small precursor component and no evidence of a postcursor one. This pulse profile is in sharp contrast to the double-peaked morphology observed during an observing campaign approximately 120 days preceding ours. Along with this change in the integrated pulse profile shape, we also measure a slower spin-down rate compared to the end of that preceding campaign. Together, these differences suggest that a mode-switching event likely occurred between the end of that campaign and the start of ours. Finally, we derived a phase-connected timing solution from our data, from which we inferred a characteristic age of approximately 2500 years, about 2.5 times older than the most recent published estimate, and a surface dipole magnetic field strength of roughly 1 x 10^14 G, nearly three times weaker. These updated estimates reflect the short-term variations in the magnetar's spin-down rate, from which both its age and magnetic field strength are inferred, rather than intrinsic changes in the magnetar itself. |
| title | The Timing Evolution of the Magnetar Swift J1818.0-1607 During a Period of Reduced Activity |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2507.19698 |