FAST Reveals New Evidence for M94 as a Merger
We report the first high-sensitivity H i observation toward the spiral galaxy M94 with the Five-hundred-meter Aperture Spherical radio Telescope. From these observations, we discovered that M94 has a very extended H i disk, twice larger than that observed by THINGS, which is accompanied by a H i fil...
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acdcf5 |
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| author | Ruilei Zhou Ming Zhu Yanbin Yang Haiyang Yu Lixia Yuan Peng Jiang Wenzhe Xi |
| author_facet | Ruilei Zhou Ming Zhu Yanbin Yang Haiyang Yu Lixia Yuan Peng Jiang Wenzhe Xi |
| author_sort | Ruilei Zhou |
| collection | DOAJ |
| description | We report the first high-sensitivity H i observation toward the spiral galaxy M94 with the Five-hundred-meter Aperture Spherical radio Telescope. From these observations, we discovered that M94 has a very extended H i disk, twice larger than that observed by THINGS, which is accompanied by a H i filament and seven high velocity clouds (HVCs) at different distances. The projected distances of these clouds and filaments are less than 50 kpc from the galactic center. We measured a total integrated flux (including all clouds/filament) of 127.3 ( ±1) Jy km s ^−1 , corresponding to a H i mass of (6.51 ± 0.06)×10 ^8 M _⊙ , which is 63.0% more than that observed by THINGS. By comparing numerical simulations with the H i maps and the optical morphology of M94, we suggest that M94 is likely a remnant of a major merger of two galaxies, and the HVCs and H i filament could be the tidal features that originated from the first collision of the merger, which happened about 5 Gyr ago. Furthermore, we found a seemingly isolated H i cloud at a projection distance of 109 kpc without any optical counterpart detected. We discuss the possibilities of the origin of this cloud, such as dark dwarf galaxy and RELHIC (REionization-Limited H i Cloud). Our results demonstrate that high-sensitivity and wide-field H i imaging is important in revealing diffuse cold gas structures and tidal debris, which is crucial to understand the dynamical evolution of galaxies. |
| format | Article |
| id | doaj-art-1457973d2c5e49dfba424142a2f848f7 |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-1457973d2c5e49dfba424142a2f848f72025-08-20T03:10:21ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01952213010.3847/1538-4357/acdcf5FAST Reveals New Evidence for M94 as a MergerRuilei Zhou0https://orcid.org/0009-0009-0581-5237Ming Zhu1https://orcid.org/0000-0001-6083-956XYanbin Yang2https://orcid.org/0000-0001-7949-3407Haiyang Yu3https://orcid.org/0000-0001-9838-7159Lixia Yuan4https://orcid.org/0000-0003-0804-9055Peng Jiang5https://orcid.org/0000-0002-5387-7952Wenzhe Xi6National Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Beijing 100101, People’s Republic of China ; mz@nao.cas.cn; University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China; CAS Key Laboratory of FAST, National FAST, National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Beijing 100101, People’s Republic of China ; mz@nao.cas.cn; University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China; CAS Key Laboratory of FAST, National FAST, National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China; Guizhou Radio Astronomical Observatory, Guizhou University , Guiyang 550000, People’s Republic of ChinaGEPI, Observatoire de Paris , CNRS, Place Jules Janssen F-92195, Meudon, FranceNational Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Beijing 100101, People’s Republic of China ; mz@nao.cas.cn; University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China; CAS Key Laboratory of FAST, National FAST, National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of ChinaPurple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences , 10 Yuanhua Road, Qixia District, Nanjing 210033, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Beijing 100101, People’s Republic of China ; mz@nao.cas.cn; CAS Key Laboratory of FAST, National FAST, National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China; Guizhou Radio Astronomical Observatory, Guizhou University , Guiyang 550000, People’s Republic of ChinaUniversity of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China; Yunnan Observatories, Chinese Academy of Sciences , Kunming 650011, People’s Republic of ChinaWe report the first high-sensitivity H i observation toward the spiral galaxy M94 with the Five-hundred-meter Aperture Spherical radio Telescope. From these observations, we discovered that M94 has a very extended H i disk, twice larger than that observed by THINGS, which is accompanied by a H i filament and seven high velocity clouds (HVCs) at different distances. The projected distances of these clouds and filaments are less than 50 kpc from the galactic center. We measured a total integrated flux (including all clouds/filament) of 127.3 ( ±1) Jy km s ^−1 , corresponding to a H i mass of (6.51 ± 0.06)×10 ^8 M _⊙ , which is 63.0% more than that observed by THINGS. By comparing numerical simulations with the H i maps and the optical morphology of M94, we suggest that M94 is likely a remnant of a major merger of two galaxies, and the HVCs and H i filament could be the tidal features that originated from the first collision of the merger, which happened about 5 Gyr ago. Furthermore, we found a seemingly isolated H i cloud at a projection distance of 109 kpc without any optical counterpart detected. We discuss the possibilities of the origin of this cloud, such as dark dwarf galaxy and RELHIC (REionization-Limited H i Cloud). Our results demonstrate that high-sensitivity and wide-field H i imaging is important in revealing diffuse cold gas structures and tidal debris, which is crucial to understand the dynamical evolution of galaxies.https://doi.org/10.3847/1538-4357/acdcf5Galaxy evolutionGalaxy interactionsGalaxy kinematicsGalaxy dynamicsH I regions |
| spellingShingle | Ruilei Zhou Ming Zhu Yanbin Yang Haiyang Yu Lixia Yuan Peng Jiang Wenzhe Xi FAST Reveals New Evidence for M94 as a Merger The Astrophysical Journal Galaxy evolution Galaxy interactions Galaxy kinematics Galaxy dynamics H I regions |
| title | FAST Reveals New Evidence for M94 as a Merger |
| title_full | FAST Reveals New Evidence for M94 as a Merger |
| title_fullStr | FAST Reveals New Evidence for M94 as a Merger |
| title_full_unstemmed | FAST Reveals New Evidence for M94 as a Merger |
| title_short | FAST Reveals New Evidence for M94 as a Merger |
| title_sort | fast reveals new evidence for m94 as a merger |
| topic | Galaxy evolution Galaxy interactions Galaxy kinematics Galaxy dynamics H I regions |
| url | https://doi.org/10.3847/1538-4357/acdcf5 |
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