Magnetic field properties of the SNR HB 9
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866918026215948288 |
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| author | Xiao, Li Zhu, Ming Sun, Xiao-Hui Reich, Wolfgang Reich, Patricia Jiang, Peng Sun, Chun |
| author_facet | Xiao, Li Zhu, Ming Sun, Xiao-Hui Reich, Wolfgang Reich, Patricia Jiang, Peng Sun, Chun |
| contents | We aim to study the polarization and magnetic field properties of the SNR HB 9 using new 21-cm continuum cube data from the Five-hundred-meter Aperture Spherical radio telescope (FAST). We computed the Faraday depth at 21 cm, and re-analyzed the rotation measures (RMs) of HB 9 using in addition Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data. FAST total-intensity images of two subbands are decomposed into components of multiple angular scales to check spectral-index variation via temperature versus temperature plots (TT-plots). The filamentary emission has a spectral index ($S\simν^α$) of $α=-$0.52, corresponding to freshly accelerated relativistic electrons. The diffuse emission has a steeper spectrum of $α=-$0.63, corresponding to confined electrons that are no longer accelerated. The FAST detected 1385-MHz polarized emission might come from a thin layer in the outer envelope of the shells, with a Faraday depth of 4-28 rad m$^{-2}$ from the Faraday rotation synthesis result. The RMs derived from the Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data show about 70 rad m$^{-2}$ in the eastern and northern shell, and 124 rad m$^{-2}$ in the inner and southern patches. The regular magnetic field is about 5$-$8 $μ$G over the remnant. The northern shell shows depolarization at 2695 MHz relative to the 4800-MHz polarization data, indicating an additional random magnetic field of 12 $μ$G on the scale of 0.6 pc. The shock wave might have entered the dense gas environment in the northern-shell region and has driven turbulence to cause depolarization at 2695 MHz. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_09125 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Magnetic field properties of the SNR HB 9 Xiao, Li Zhu, Ming Sun, Xiao-Hui Reich, Wolfgang Reich, Patricia Jiang, Peng Sun, Chun Astrophysics of Galaxies We aim to study the polarization and magnetic field properties of the SNR HB 9 using new 21-cm continuum cube data from the Five-hundred-meter Aperture Spherical radio telescope (FAST). We computed the Faraday depth at 21 cm, and re-analyzed the rotation measures (RMs) of HB 9 using in addition Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data. FAST total-intensity images of two subbands are decomposed into components of multiple angular scales to check spectral-index variation via temperature versus temperature plots (TT-plots). The filamentary emission has a spectral index ($S\simν^α$) of $α=-$0.52, corresponding to freshly accelerated relativistic electrons. The diffuse emission has a steeper spectrum of $α=-$0.63, corresponding to confined electrons that are no longer accelerated. The FAST detected 1385-MHz polarized emission might come from a thin layer in the outer envelope of the shells, with a Faraday depth of 4-28 rad m$^{-2}$ from the Faraday rotation synthesis result. The RMs derived from the Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data show about 70 rad m$^{-2}$ in the eastern and northern shell, and 124 rad m$^{-2}$ in the inner and southern patches. The regular magnetic field is about 5$-$8 $μ$G over the remnant. The northern shell shows depolarization at 2695 MHz relative to the 4800-MHz polarization data, indicating an additional random magnetic field of 12 $μ$G on the scale of 0.6 pc. The shock wave might have entered the dense gas environment in the northern-shell region and has driven turbulence to cause depolarization at 2695 MHz. |
| title | Magnetic field properties of the SNR HB 9 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2503.09125 |