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Peer-reviewedCC BY 4.0Monthly Notices of the Royal Astronomical Society

Extended 2.25/8.60 GHz Observations of the Magnetar Swift J1818.0−1607

  • Zhi-Peng Huang1,2
  • Zhen Yan3,4,5
  • Zhi-Qiang Shen3,4,5
  • Hao Tong6
  • Wei-Yang Wang7
  • Xiao-Yu Lai1,2
  • Rong-Bing Zhao3,5
  • Ya-Jun Wu3,5
  • Rui Wang8
  • Xiao-Wei Wang3,4
  • Fan Yang3,9
  • Chu-Yuan Zhang3,4
2 more authors
  • Zhen-Long Liao3,4
  • Yang-Yang Lin3,10
10 affiliations
  1. 1School of Optoelectronic Information Engineering, Hubei University of Education , Wuhan 430205 ,
  2. 2Institute of Astronomy and High Energy Physics, Hubei University of Education , Wuhan 430205 ,
  3. 3Shanghai Astronomical Observatory, Chinese Academy of Sciences , Shanghai 200030 ,
  4. 4School of Astronomy and Space Sciences, University of Chinese Academy of Sciences , Beijing 100049 ,
  5. 5State Key Laboratory of Radio Astronomy and Technology, Shanghai Astronomical Observatory, Chinese Academy of Sciences , Shanghai 200030 ,
  6. 6School of Physics and Materials Science Department of Astronomy, , Guangzhou University, Guangzhou 510006 ,
  7. 7University of Chinese Academy of Sciences , Beijing 100049 ,
  8. 8School of Information Engineering, Sanming University , Sanming 365004 ,
  9. 9School of Physical Science and Technology , ShanghaiTech University, Shanghai 201210 ,
  10. 10College of Science, Shanghai University , Shanghai 200444 ,
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Abstract

We present the long-term rotational evolution and radio emission properties of the magnetar Swift J1818.0−1607, using simultaneous 2.25/8.60 GHz observations obtained with the Shanghai Tian Ma Radio Telescope from MJD 58936 to 59427. The average pulse profiles exhibit significant evolution with time and frequency, attributable to relative changes in the leading, central, and trailing emission components. The magnetar generally spins down with an average rate of −1.65(4) × 10−11 s−2, with the magnitude of the spin-down rate first increasing and then decreasing over the monitoring span. The overall flux density shows an initial rise followed by a decline, with sporadic variability superimposed; the variations at 2.25 and 8.60 GHz are broadly consistent across most epochs. The two-point spectral index increased from α ≃ −1.8 shortly after the outburst to near-zero values around MJD 59030–59050, followed by repeated decreases and increases. Despite this variability, 41 of the 54 two-point spectral-index measurements in the later campaign have α > −1. Three component-dependent types of mode changing are identified: Type I, involving primarily intensity changes in the central component; Type II, involving central and trailing components; and Type III, involving leading and central components. All three classes include events showing a corresponding component response in the other observing band, with event-dependent response strengths and directions. Type I variations are generally more pronounced at 8.60 GHz than at 2.25 GHz.

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Cite

BibTeXRIS
BibTeX
@article{huang2026extended,
  title = {{Extended 2.25/8.60 GHz Observations of the Magnetar Swift J1818.0−1607}},
  author = {Zhi-Peng Huang and Zhen Yan and Zhi-Qiang Shen and Hao Tong and Wei-Yang Wang and Xiao-Yu Lai and Rong-Bing Zhao and Ya-Jun Wu and Rui Wang and Xiao-Wei Wang and Fan Yang and Chu-Yuan Zhang and Zhen-Long Liao and Yang-Yang Lin},
  journal = {Monthly Notices of the Royal Astronomical Society},
  year = {2026},
  month = nov,
  doi = {10.1093/mnras/stag2092},
  url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2092/9012727},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Extended 2.25/8.60 GHz Observations of the Magnetar Swift J1818.0−1607
AU  - Zhi-Peng Huang
AU  - Zhen Yan
AU  - Zhi-Qiang Shen
AU  - Hao Tong
AU  - Wei-Yang Wang
AU  - Xiao-Yu Lai
AU  - Rong-Bing Zhao
AU  - Ya-Jun Wu
AU  - Rui Wang
AU  - Xiao-Wei Wang
AU  - Fan Yang
AU  - Chu-Yuan Zhang
AU  - Zhen-Long Liao
AU  - Yang-Yang Lin
PY  - 2026
DA  - 2026/11/04
JO  - Monthly Notices of the Royal Astronomical Society
DO  - 10.1093/mnras/stag2092
UR  - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2092/9012727
AB  - We present the long-term rotational evolution and radio emission properties of the magnetar Swift J1818.0−1607, using simultaneous 2.25/8.60 GHz observations obtained with the Shanghai Tian Ma Radio Telescope from MJD 58936 to 59427. The average pulse profiles exhibit significant evolution with time and frequency, attributable to relative changes in the leading, central, and trailing emission components. The magnetar generally spins down with an average rate of −1.65(4) × 10−11 s−2, with the magnitude of the spin-down rate first increasing and then decreasing over the monitoring span. The overall flux density shows an initial rise followed by a decline, with sporadic variability superimposed; the variations at 2.25 and 8.60 GHz are broadly consistent across most epochs. The two-point spectral index increased from α ≃ −1.8 shortly after the outburst to near-zero values around MJD 59030–59050, followed by repeated decreases and increases. Despite this variability, 41 of the 54 two-point spectral-index measurements in the later campaign have α > −1. Three component-dependent types of mode changing are identified: Type I, involving primarily intensity changes in the central component; Type II, involving central and trailing components; and Type III, involving leading and central components. All three classes include events showing a corresponding component response in the other observing band, with event-dependent response strengths and directions. Type I variations are generally more pronounced at 8.60 GHz than at 2.25 GHz.
SN  - 0035-8711
SN  - 1365-2966
ER  -