Deep Andromeda JCMT-SCUBA2 Observations. The Submillimeter Maps and Giant Molecular Clouds
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| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| author | Jiao, Sihan Wu, Jingwen Liu, Hauyu Baobab Tsai, Chao-Wei Lin, Yuxin Li, Di Zhang, Zhi-Yu Cheng, Yu Feng, Linjing Beuther, Henrik Wang, Junzhi Lin, Lihwai Brok, Jakob den Zhang, Ludan Xu, Fengwei Meng, Fanyi Li, Zongnan Keenan, Ryan P. Yu, Si-Yue Yu, Niankun Zheng, Zheng Liu, Junhao Liu, Yuxiang Ruan, Hao Deng, Fangyuan Xiong, Yuanzhen |
| author_facet | Jiao, Sihan Wu, Jingwen Liu, Hauyu Baobab Tsai, Chao-Wei Lin, Yuxin Li, Di Zhang, Zhi-Yu Cheng, Yu Feng, Linjing Beuther, Henrik Wang, Junzhi Lin, Lihwai Brok, Jakob den Zhang, Ludan Xu, Fengwei Meng, Fanyi Li, Zongnan Keenan, Ryan P. Yu, Si-Yue Yu, Niankun Zheng, Zheng Liu, Junhao Liu, Yuxiang Ruan, Hao Deng, Fangyuan Xiong, Yuanzhen |
| contents | We have carried out unprecedentedly deep, nearly confusion-limited JCMT-SCUBA2 mapping observations on the nearest spiral galaxy, M31 (Andromeda). The 850 $μ$m image with a $\sim$50 pc resolution yields a comprehensive catalog of 383 giant molecular clouds (GMCs) that are associated with the spiral arms. In addition, it unveiled a population of 189 compact inter-arm GMCs in M31, which are mostly unresolved or marginally resolved. The masses of all these GMCs are in the range of 2$\times$10$^4$ -- 6$\times$10$^6$ $M_{\odot}$; the sizes are in the range of 30--130 pc. They follow a mass-size correlation, $M$ $\propto$ $R_{c}$$^{2.5}$. The inter-arm GMCs are systematically less massive, more diffuse, colder, and have lower star-forming efficiency (SFE) than on-arm GMCs. Moreover, within individual spatially resolved on-arm and off-arm M31 GMCs, the SFE is considerably lower than the SFE in molecular clouds in main sequence and green valley galaxies. Follow-up investigations on M31 GMCs may provide clues for how star formation may be quenched in galactic environments. Finally, we reconstrained the dust opacity spectral index $β$ in the M31 galaxy by combining our new JCMT observations with archival Herschel and Planck data and found that the radial variation of $β$ may not be as large as was proposed by previous studies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_14360 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Deep Andromeda JCMT-SCUBA2 Observations. The Submillimeter Maps and Giant Molecular Clouds Jiao, Sihan Wu, Jingwen Liu, Hauyu Baobab Tsai, Chao-Wei Lin, Yuxin Li, Di Zhang, Zhi-Yu Cheng, Yu Feng, Linjing Beuther, Henrik Wang, Junzhi Lin, Lihwai Brok, Jakob den Zhang, Ludan Xu, Fengwei Meng, Fanyi Li, Zongnan Keenan, Ryan P. Yu, Si-Yue Yu, Niankun Zheng, Zheng Liu, Junhao Liu, Yuxiang Ruan, Hao Deng, Fangyuan Xiong, Yuanzhen Astrophysics of Galaxies We have carried out unprecedentedly deep, nearly confusion-limited JCMT-SCUBA2 mapping observations on the nearest spiral galaxy, M31 (Andromeda). The 850 $μ$m image with a $\sim$50 pc resolution yields a comprehensive catalog of 383 giant molecular clouds (GMCs) that are associated with the spiral arms. In addition, it unveiled a population of 189 compact inter-arm GMCs in M31, which are mostly unresolved or marginally resolved. The masses of all these GMCs are in the range of 2$\times$10$^4$ -- 6$\times$10$^6$ $M_{\odot}$; the sizes are in the range of 30--130 pc. They follow a mass-size correlation, $M$ $\propto$ $R_{c}$$^{2.5}$. The inter-arm GMCs are systematically less massive, more diffuse, colder, and have lower star-forming efficiency (SFE) than on-arm GMCs. Moreover, within individual spatially resolved on-arm and off-arm M31 GMCs, the SFE is considerably lower than the SFE in molecular clouds in main sequence and green valley galaxies. Follow-up investigations on M31 GMCs may provide clues for how star formation may be quenched in galactic environments. Finally, we reconstrained the dust opacity spectral index $β$ in the M31 galaxy by combining our new JCMT observations with archival Herschel and Planck data and found that the radial variation of $β$ may not be as large as was proposed by previous studies. |
| title | Deep Andromeda JCMT-SCUBA2 Observations. The Submillimeter Maps and Giant Molecular Clouds |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2511.14360 |