Dark matter (DM) as a Bose–Einstein condensate, such as the axionic scalar field particles of String Theory, can explain the coldness of DM on large scales. Pioneering simulations in this context predict a rich wave-like structure, with a ground state soliton core in every galaxy surrounded by a halo of excited states that interfere on the de Broglie scale. This de Broglie scale is largest for the low-mass galaxies as momentum is lower, providing a simple explanation for the wide cores of dwarf spheroidal galaxies. Here we extend these ‘wave dark matter’ (ψDM) predictions to the newly discovered class of ‘ultra-diffuse galaxies’ (UDG) that resemble dwarf spheroidal galaxies but with more extended stellar profiles. Currently, the best-studied example, ‘Dragon Fly 44’ (DF44), has a uniform velocity dispersion of ≃33 km s−1, extending to at least 3 kpc, that we show is reproduced by our ψDM simulations with a soliton radius of ≃0.5 kpc. In the ψDM context, we show that relatively flat dispersion profile of DF44 lies between massive galaxies with compact dense solitons, as may be present in the Milky Way on a scale of 100 pc and lower mass galaxies where the velocity dispersion declines centrally within a wide, low-density soliton, like Antlia II, of radius 3 kpc.

中文翻译：

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波动暗物质和超扩散星系

暗物质 (DM) 作为玻色-爱因斯坦凝聚体，例如弦理论的轴子标量场粒子，可以在大尺度上解释 DM 的冷性。在这种情况下，开创性的模拟预测了一个丰富的波状结构，每个星系中都有一个基态孤子核心，周围环绕着在德布罗意尺度上干扰的激发态光环。这个德布罗意尺度对于低质量星系来说是最大的，因为动量较低，为矮球形星系的宽核心提供了简单的解释。在这里，我们将这些“波暗物质”（ψDM）预测扩展到新发现的“超扩散星系”（UDG）类，它类似于矮球形星系，但具有更多扩展的恒星轮廓。目前，研究得最好的例子，“Dragon Fly 44”（DF44），具有 ≃33 km s−1 的均匀速度色散，扩展到至少 3 kpc，我们展示的 ψDM 模拟再现了孤子半径为≃0.5 kpc。在 ψDM 上下文中，我们表明 DF44 相对平坦的色散分布位于具有致密致密孤子的大质量星系之间，这可能存在于银河系中，规模为 100 pc 和速度色散在较宽范围内集中下降的低质量星系。 ，低密度孤子，如 Antlia II，半径为 3 kpc。