Scalar field dark matter (SFDM), comprised of ultralight (≳ 10−22 eV) bosons, is distinguished from massive (≳GeV), collisionless cold dark matter (CDM) by its novel structure-formation dynamics as Bose–Einstein condensate (BEC) and quantum superfluid with wave-like properties, described by the Gross-Pitaevskii and Poisson (GPP) equations. In the free-field (‘fuzzy’) limit of SFDM (FDM), structure is inhibited below the de Broglie wavelength λdeB, but resembles CDM on larger scales. Virialized haloes have ‘solitonic’ cores of radius ∼λdeB that follow the ground-state attractor solution of GPP, surrounded by CDM-like envelopes. As superfluid, SFDM is irrotational (vorticity-free) but can be unstable to vortex formation. We previously showed this can happen in halo cores, from angular momentum arising during structure formation, when repulsive self-interaction (SI) is present to support them out to a second length scale λSI with λSI > λdeB (the Thomas–Fermi regime), but only if SI is strong enough. This suggested FDM cores ($ {\rm without}$ SI) would not form vortices. FDM simulations later found vortices, but only outside halo cores, consistent with our previous suggestion based upon TF-regime analysis. We extend that analysis now to FDM, to show explicitly that vortices should not arise in solitonic cores from angular momentum, modelling them as either Gaussian spheres, or ( n = 2)-polytropic, irrotational Riemann-S ellipsoids. We find that, for typical halo spin parameters, angular momentum per particle is below ℏ, the minimum required even for one singly-quantized vortex in the centre. Even for higher angular momentum, however, vortex formation is not energetically favoured.

中文翻译：

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角动量和模糊暗物质晕核心中没有涡旋

标量场暗物质 (SFDM) 由超轻 (≳ 10−22 eV) 玻色子组成，其与大质量 (≳GeV)、无碰撞冷暗物质 (CDM) 的区别在于其具有玻色-爱因斯坦凝聚体 (BEC) 的新颖结构形成动力学) 和具有波状特性的量子超流体，由 Gross-Pitaevskii 和 Poisson (GPP) 方程描述。在 SFDM (FDM) 的自由场（“模糊”）极限中，结构在德布罗意波长 λdeB 以下被抑制，但在更大的尺度上类似于 CDM。Virialized 晕具有半径为~λdeB 的“孤子”核心，遵循 GPP 的基态吸引子解决方案，被类似 CDM 的包络包围。作为超流体，SFDM 是无旋的（无涡流），但对涡流的形成可能不稳定。我们之前已经证明，这可能发生在晕核中，来自结构形成过程中产生的角动量，当存在排斥性自相互作用 (SI) 以支持它们到第二长度尺度 λSI 时，λSI > λdeB（Thomas-Fermi 方案），但前提是 SI 足够强。这表明 FDM 核心（$ {\rm 没有}$ SI）不会形成涡流。FDM 模拟后来发现了涡流，但仅在晕核之外，这与我们之前基于 TF 区域分析的建议一致。我们现在将该分析扩展到 FDM，以明确表明涡旋不应在角动量的孤子核中出现，将它们建模为高斯球体或 (n = 2)-多向性、无旋黎曼-S 椭球体。我们发现，对于典型的晕圈自旋参数，每个粒子的角动量低于 ℏ，即使是中心的一个单量子化涡旋也需要的最小值。然而，即使对于更高的角动量，