论文标题
域壁网络的功率谱及其对各向同性和各向异性宇宙双折射的影响
Power spectrum of domain-wall network and its implications for isotropic and anisotropic cosmic birefringence
论文作者
论文摘要
最近，基于对普朗克卫星数据的新分析，已经报道了宇宙微波背景光子极化的均匀旋转的迹象，称为各向同性宇宙双折射。所建议的极化旋转角度约为$ 0.2-0.4 $度，强烈表明它取决于精细的结构常数，这可以自然地在非常宽的参数范围内由轴状粒子的域壁上的域壁上解释。有趣的是，轴突状的颗粒结构壁不仅预测了各向异性宇宙双折射，而且还预测了各向异性的，它反映了最后一个散射表面上类似轴突的粒子场的空间分布。在这封信中，我们对扩展宇宙中域壁的形成和演变进行晶格模拟，并首次获得构成域壁的标量场的两点相关函数和功率谱。我们发现，虽然功率谱通常与基于随机壁分布的分析预测一致，但与哈勃半径相对应的尺度上有一个主要的过量。将我们的结果应用于各向异性宇宙双折射，我们预测了由轴突样颗粒结构壁诱导的旋转角度的功率谱，并表明它在宇宙微波背景的未来观察结果范围内。
Recently, based on a novel analysis of the Planck satellite data, a hint of a uniform rotation of the polarization of cosmic microwave background photons, called isotropic cosmic birefringence, has been reported. The suggested rotation angle of polarization of about $0.2-0.4$ degrees strongly suggests that it is determined by the fine structure constant, which can be naturally explained over a very wide parameter range by the domain walls of axion-like particles. Interestingly, the axion-like particle domain walls predict not only isotropic cosmic birefringence but also anisotropic one that reflects the spatial distribution of the axion-like particle field on the last scattering surface. In this Letter, we perform lattice simulations of the formation and evolution of domain walls in the expanding universe and obtain for the first time the two-point correlation function and power spectrum of the scalar field that constitutes the domain walls. We find that while the power spectrum is generally consistent with analytical predictions based on random wall distributions, there is a predominant excess on the scale corresponding to the Hubble radius. Applying our results to the anisotropic cosmic birefringence, we predict the power spectrum of the rotation angles induced by the axion-like particle domain walls and show that it is within the reach of future observations of the cosmic microwave background.
