In the standard cosmological model, dark matter drives the structure formation of galaxies and constructs potential wells within which galaxies may form. The baryon fraction in dark halos can reach the Universal value (15.7%) in massive clusters and decreases rapidly as the mass of the system decreases^1,2. The formation of dwarf galaxies is sensitive both to baryonic processes and the properties of dark matter owing to the shallow potential wells in which they form. In dwarf galaxies in the Local Group, dark matter dominates the mass content even within their optical-light half-radii (r_e ≈ 1 kpc)^3,4. However, recently it has been argued that not all dwarf galaxies are dominated by dark matter^5,6,7. Here we report 19 dwarf galaxies that could consist mainly of baryons up to radii well beyond r_e, at which point they are expected to be dominated by dark matter. Of these, 14 are isolated dwarf galaxies, free from the influence of nearby bright galaxies and high-density environments. This result provides observational evidence that could challenge the formation theory of low-mass galaxies within the framework of standard cosmology. Further observations, in particular deep imaging and spatially resolved kinematics, are needed to constrain the baryon fraction better in such galaxies.

在标准宇宙学模型中，暗物质驱动星系的结构形成，并构造可能在其中形成星系的潜在阱。黑暗光晕中的重子分数在大规模簇中可以达到通用值（15.7％），并且随着系统质量的降低^1,2迅速降低。矮星系的形成对重子过程和暗物质的性质都很敏感，这是由于它们形成的势阱很浅。在本地组矮星系，暗物质支配即使在质量含量它们的光学光半半径（ř _Ë  ≈1 KPC）^3,4。然而，最近有人争辩说，并非所有矮星系都由暗物质控制[ ^5,6,7]。。在这里，我们报告19的矮星系，可能主要由重子可达半径远远超出[R _é，在这一点上，他们预计将通过暗物质为主。其中，有14个是孤立的矮星系，不受附近明亮的星系和高密度环境的影响。这一结果提供了可能在标准宇宙学框架内挑战低质量星系形成理论的观测证据。需要进一步的观察，特别是深度成像和空间分辨运动学，以更好地限制此类星系中的重子分数。