FAST Reveals New Evidence for M94 as a Merger - Galaxies, Etoiles, Physique, Instrumentation
Article Dans Une Revue The Astrophysical Journal Année : 2023

FAST Reveals New Evidence for M94 as a Merger

Ruilei Zhou
  • Fonction : Auteur
Ming Zhu
  • Fonction : Auteur
Haiyang Yu
  • Fonction : Auteur
Lixia Yuan
  • Fonction : Auteur
Peng Jiang
  • Fonction : Auteur
Wenzhe Xi
  • Fonction : Auteur

Résumé

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)×108 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.
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insu-04848723 , version 1 (20-12-2024)

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Ruilei Zhou, Ming Zhu, Yanbin Yang, Haiyang Yu, Lixia Yuan, et al.. FAST Reveals New Evidence for M94 as a Merger. The Astrophysical Journal, 2023, 952, ⟨10.3847/1538-4357/acdcf5⟩. ⟨insu-04848723⟩
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