Buschmann Malte, Foster Joshua W, Safdi Benjamin R
Leinweber Center for Theoretical Physics, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109.
Phys Rev Lett. 2020 Apr 24;124(16):161103. doi: 10.1103/PhysRevLett.124.161103.
Ultracompact dark matter (DM) minihalos at masses at and below 10^{-12} M_{⊙} arise in axion DM models where the Peccei-Quinn (PQ) symmetry is broken after inflation. The minihalos arise from density perturbations that are generated from the nontrivial axion self-interactions during and shortly after the collapse of the axion-string and domain-wall network. We perform high-resolution simulations of this scenario starting at the epoch before the PQ phase transition and ending at matter-radiation equality. We characterize the spectrum of primordial perturbations that are generated and comment on implications for efforts to detect axion DM. We also measure the DM density at different simulated masses and argue that the correct DM density is obtained for m_{a}=25.2±11.0 μeV.
质量等于及低于(10^{-12}M_{⊙})的超紧凑暗物质（DM）微晕出现在轴子暗物质模型中，其中佩切伊 - 奎因（PQ）对称性在暴胀之后被打破。这些微晕源于轴子弦和畴壁网络坍缩期间及之后不久由非平凡轴子自相互作用产生的密度扰动。我们从PQ相变之前的时期开始，到物质 - 辐射相等时结束，对这种情况进行了高分辨率模拟。我们刻画了所产生的原初扰动的频谱，并评论了对探测轴子暗物质的影响。我们还测量了不同模拟质量下的暗物质密度，并认为对于(m_{a}=25.2±11.0 μeV)可得到正确的暗物质密度。
