Network of velocity-coherent filaments formed by supersonic turbulence in a very-high-velocity HI cloud
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arXiv
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| Auteurs principaux: | , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866915326361337856 |
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| author | Liu, Xunchuan Liu, Tie Li, Pak-Shing Mai, Xiaofeng Henkel, Christian Goldsmith, Paul F. Qin, Sheng-Li Gong, Yan Lu, Xing Xu, Fengwei Luo, Qiuyi Liu, Hong-Li Zhang, Tianwei Cheng, Yu Di, Yihuan Wu, Yuefang Gu, Qilao Tang, Ningyu Yang, Aiyuan Shen, Zhiqiang |
| author_facet | Liu, Xunchuan Liu, Tie Li, Pak-Shing Mai, Xiaofeng Henkel, Christian Goldsmith, Paul F. Qin, Sheng-Li Gong, Yan Lu, Xing Xu, Fengwei Luo, Qiuyi Liu, Hong-Li Zhang, Tianwei Cheng, Yu Di, Yihuan Wu, Yuefang Gu, Qilao Tang, Ningyu Yang, Aiyuan Shen, Zhiqiang |
| contents | The warm neutral medium (WNM) was thought to be subsonically/transonically turbulent, and it lacks a network of intertwined filaments that are commonly seen in both molecular clouds and cold neutral medium (CNM). Here, we report HI~21 cm line observations of a very-high-velocity (-330 km s$^{-1}$ $<V_{\rm LSR}<$ -250 km s$^{-1}$) cloud (VHVC), using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) with unprecedented resolution and sensitivity. For the first time, such a VHVC is clearly revealed to be a supersonic WNM system consisting of a network of velocity-coherent HI~filaments. The filaments are in the forms of slim curves, hubs, and webs, distributed in different layers within the position-position-velocity ({\it ppv}) data cube. The entire cloud has skewed log-normal probability distribution of column density and the filaments themselves show asymmetrical radial density profiles, indicating shock compression by supersonic magnetohydrodynamic (MHD) turbulence, as is also confirmed by our MHD simulation (sonic Mach number $M_{\rm s}=3$ and Alfvén Mach number $M_{\rm A}=1$). This work suggests that hierarchical filaments can be established by shocks in a low-density WNM, where gravity is negligible, offering a viable pathway to structure formation in the earliest evolutionary phases of the interstellar medium (ISM). |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_10897 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Network of velocity-coherent filaments formed by supersonic turbulence in a very-high-velocity HI cloud Liu, Xunchuan Liu, Tie Li, Pak-Shing Mai, Xiaofeng Henkel, Christian Goldsmith, Paul F. Qin, Sheng-Li Gong, Yan Lu, Xing Xu, Fengwei Luo, Qiuyi Liu, Hong-Li Zhang, Tianwei Cheng, Yu Di, Yihuan Wu, Yuefang Gu, Qilao Tang, Ningyu Yang, Aiyuan Shen, Zhiqiang Astrophysics of Galaxies Solar and Stellar Astrophysics The warm neutral medium (WNM) was thought to be subsonically/transonically turbulent, and it lacks a network of intertwined filaments that are commonly seen in both molecular clouds and cold neutral medium (CNM). Here, we report HI~21 cm line observations of a very-high-velocity (-330 km s$^{-1}$ $<V_{\rm LSR}<$ -250 km s$^{-1}$) cloud (VHVC), using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) with unprecedented resolution and sensitivity. For the first time, such a VHVC is clearly revealed to be a supersonic WNM system consisting of a network of velocity-coherent HI~filaments. The filaments are in the forms of slim curves, hubs, and webs, distributed in different layers within the position-position-velocity ({\it ppv}) data cube. The entire cloud has skewed log-normal probability distribution of column density and the filaments themselves show asymmetrical radial density profiles, indicating shock compression by supersonic magnetohydrodynamic (MHD) turbulence, as is also confirmed by our MHD simulation (sonic Mach number $M_{\rm s}=3$ and Alfvén Mach number $M_{\rm A}=1$). This work suggests that hierarchical filaments can be established by shocks in a low-density WNM, where gravity is negligible, offering a viable pathway to structure formation in the earliest evolutionary phases of the interstellar medium (ISM). |
| title | Network of velocity-coherent filaments formed by supersonic turbulence in a very-high-velocity HI cloud |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2502.10897 |