The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly Massive Dark Matter Halos in Several Ultradiffuse Galaxies in the Virgo Cluster
The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly Massive Dark Matter Halos in Several Ultradiffuse Galaxies in the Virgo Cluster
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DOI：
10.3847/1538-4357/acd336
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
E. Toloba;L. Sales;Sungsoon Lim;E. Peng;P. Guhathakurta;J. Roediger;Kaixiang Wang;J. C. Mihos
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文献类型：
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作者：
E. Toloba;L. Sales;Sungsoon Lim;E. Peng;P. Guhathakurta;J. Roediger;Kaixiang Wang;J. C. Mihos
我们给出了处女座星系团中第一个超扩散星系(UDGs)的完整样本的Keck/Deimos光谱。我们选择处女座的所有UDG，这些UDG至少包含10个球状星团(GC)候选者，并且在大小、表面亮度和光度的比例关系上超过2.5UDG(总共10个UDG)。我们使用他们的GC卫星的径向速度来衡量每个UDG的速度离散。我们发现了一大堆星系，从一个没有暗物质迹象的UDG，到遵循早期类型星系光度-色散关系的UDG，再到打破了众所周知的光度-色散关系或U型总质光比关系的严重暗物质主导的星系的最极端例子。这表明了形成这些特殊星系的许多机制在起作用。它们中的一些可能是矮小星系最广泛的版本，而另一些则是如此极端，以至于它们似乎充斥着与银河系一致的暗物质晕，甚至更大。尽管不能完全排除银河系恒星和其他GC入侵者污染我们的GC样本的可能性，但我们对这个潜在问题的评估和模拟表明，这种可能性很低，如果存在的话，也不太可能足以解释测量到的极端分散。从这些UDG中的恒星运动学研究中得到进一步的证实将是可取的。在任何最先进的模拟中都没有这样极端的天体，这为塑造这些星系的新物理开辟了一条令人兴奋的道路。
We present Keck/DEIMOS spectroscopy of the first complete sample of ultradiffuse galaxies (UDGs) in the Virgo cluster. We select all UDGs in Virgo that contain at least 10 globular cluster (GC) candidates and are more than 2.5σ outliers in scaling relations of size, surface brightness, and luminosity (a total of 10 UDGs). We use the radial velocity of their GC satellites to measure the velocity dispersion of each UDG. We find a mixed bag of galaxies, from one UDG that shows no signs of dark matter, to UDGs that follow the luminosity–dispersion relation of early-type galaxies, to the most extreme examples of heavily dark matter–dominated galaxies that break well-known scaling relations such as the luminosity–dispersion or U-shaped total mass-to-light ratio relations. This is indicative of a number of mechanisms at play forming these peculiar galaxies. Some of them may be the most extended version of dwarf galaxies, while others are so extreme that they seem to populate dark matter halos consistent with that of the Milky Way or even larger. Even though Milky Way stars and other GC interlopers contaminating our sample of GCs cannot be fully ruled out, our assessment of this potential problem and simulations indicate that the probability is low and, if present, unlikely to be enough to explain the extreme dispersions measured. Further confirmation from stellar kinematics studies in these UDGs would be desirable. The lack of such extreme objects in any of the state-of-the-art simulations opens an exciting avenue of new physics shaping these galaxies.