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

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.

The quiescent states of V745 Sco and V3890 Sgr: VLT/X-shooter and Swift/XRT+UVOT observations
Bor Jamnik, Ulisse Munari, Nicola Masetti +2
arXiv1 Sep 2026PreprintCC BY 4.0Full textSolar & stellar physicsarXiv
Low Frequency Radio Imaging Study of PSR J1818-1607
A. Yadav, M. P. Surnis, B. C. Joshi +1
arXiv17 Sep 2026PreprintarXiv licenceFull textHigh-energy astrophysicsarXiv
Vacuum birefringence and the polarized X-ray emission from a radio magnetar
R. J. Stewart, Hoa Dinh Thi, George A. Younes +13
Nature5 Aug 2026Peer-reviewedLicence not statedFull text8 citedHigh-energy astrophysicsOpenAlex
Magnetar magnetothermal evolution with Landau-quantized electrons: enhanced Joule heating due to free electron diamagnetism and the magnetar heating problem
Peter B. Rau
arXiv21 Sep 2026PreprintCC BY 4.0Full textHigh-energy astrophysicsarXiv
Gaussian process inference of stochastic magneto-active dynamics and viscosity in Swift J1727.8-1613
Lijuan Dong, Dahai Yan, Zihan Yang +4
Astronomy & Astrophysics14 Oct 2026Peer-reviewedPublisher termsSolar & stellar physicsCrossref

Cite

BibTeX RIS

BibTeX

@misc{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},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.04935},
  eprint = {2611.04935},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.04935},
}

RIS

TY  - UNPB
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  - 2026/11/03
PB  - arXiv
DO  - 10.48550/arxiv.2611.04935
UR  - https://arxiv.org/abs/2611.04935
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.
ER  -

Abstract

Related

Cite