Unveiling the nature and fate of the almost-dark cloud AGC 226178 through H I mapping
作者：Yu-Zhu Sun, Hong-Xin Zhang, E. Brinks, Rory Smith, Fujia Li, Minsu Kim, Se–Heon Oh, Zesen Lin, Ji Hoon Kim, Weibin Sun, Tie Li, Patrick Côté, A. Boselli, Lijun Chen, Pierre–Alain Duc, Sanjaya Paudel, Matthew A. Taylor, Kaixiang Wang, Enci Wang, Lanyue Zhang, Yinghe Zhao · 发表于：Astronomy and Astrophysics · 年份：2025 · DOI：10.1051/0004-6361/202555150 · 被引用次数：3 · 研究领域：Gamma-ray bursts and supernovae、Galaxies: Formation, Evolution, Phenomena、Astronomy and Astrophysical Research
Context. The origin of extragalactic, almost dark H I clouds with extreme gas-to-stellar mass ratios remains poorly understood. Aims. We investigated the nature and fate of the almost dark cloud AGC 226178, projected within the Virgo cluster, which exhibits an H I -to-stellar mass ratio of approximately 1000. Methods. We present deep single-dish H I mapping from the Five-hundred-meter Aperture Spherical Telescope (FAST), complemented by high-resolution interferometric data from the Very Large Array (VLA), as part of the Atomic gas in Virgo Interacting Dwarf galaxies (AVID) project. Together, these observations provide the highest-quality H I analysis to date of an almost dark cloud, in terms of the combination of spatial resolution and sensitivity. Results. The FAST data reveal a short low-velocity tail extending towards the dwarf galaxy VCC 2034, which was previously proposed as a possible origin for AGC 226178. However, VCC 2034 itself exhibits a line-of-sight asymmetric H I feature and a cometary morphology that indicates a stripping event unrelated to AGC 226178. VLA observations reveal a velocity gradient across AGC 226178, along with a clumpy internal structure. The velocity dispersion within the cloud exceeds the thermal line width, indicating the presence of turbulence and/or unresolved random motions. The whole cloud cannot be gravitationally bound by the observed atomic gas alone. The resolved H I clumps follow the standard H I mass–star formation rate relation and ...