Multifrequency Radio Observations of the Magnetar Swift J1818.0--1607
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arXiv
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| Format: | Preprint |
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2025
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| author | Lewis, Evan F. Blumer, Harsha Lynch, Ryan S. McLaughlin, Maura A. |
| author_facet | Lewis, Evan F. Blumer, Harsha Lynch, Ryan S. McLaughlin, Maura A. |
| contents | We report on Green Bank Telescope observations of the radio magnetar Swift J1818.0--1607 between 820 MHz and 35 GHz, taken from six to nine months after its 2020 March outburst. We obtained multi-hour observations at six frequencies, recording polarimetric, spectral, and single-pulse information. The spectrum peaks at a frequency of $5.4 \pm 0.6$ GHz, making Swift J1818.0--1607 one of many radio magnetars which exhibit a gigahertz-peaked spectrum (GPS). The radio flux decays steeply above the peak frequency, with in-band spectral indices $α< -2.3 $ above 9 GHz. The emission is highly ($> 50\%$) linearly polarized, with a lower degree ($< 30\%$) of circular polarization which can change handedness between single pulses. Across the frequency range of our observations, the time-integrated radio profiles share a common shape: a narrow ``pulsar-like'' central component flanked by ``magnetar-like'' components comprised of bright, spiky subpulses. The outer profile components exhibit larger degrees of flux modulation and flatter spectral indices when compared to the central pulse component. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_15200 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Multifrequency Radio Observations of the Magnetar Swift J1818.0--1607 Lewis, Evan F. Blumer, Harsha Lynch, Ryan S. McLaughlin, Maura A. High Energy Astrophysical Phenomena We report on Green Bank Telescope observations of the radio magnetar Swift J1818.0--1607 between 820 MHz and 35 GHz, taken from six to nine months after its 2020 March outburst. We obtained multi-hour observations at six frequencies, recording polarimetric, spectral, and single-pulse information. The spectrum peaks at a frequency of $5.4 \pm 0.6$ GHz, making Swift J1818.0--1607 one of many radio magnetars which exhibit a gigahertz-peaked spectrum (GPS). The radio flux decays steeply above the peak frequency, with in-band spectral indices $α< -2.3 $ above 9 GHz. The emission is highly ($> 50\%$) linearly polarized, with a lower degree ($< 30\%$) of circular polarization which can change handedness between single pulses. Across the frequency range of our observations, the time-integrated radio profiles share a common shape: a narrow ``pulsar-like'' central component flanked by ``magnetar-like'' components comprised of bright, spiky subpulses. The outer profile components exhibit larger degrees of flux modulation and flatter spectral indices when compared to the central pulse component. |
| title | Multifrequency Radio Observations of the Magnetar Swift J1818.0--1607 |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2502.15200 |