论文标题
原始磁场引起的小型CMB各向异性
Small-scale CMB anisotropies induced by the primordial magnetic fields
论文作者
论文摘要
早期宇宙中产生的原始磁场（PMF）预计将是大规模宇宙磁场的起源。由于电磁力和重力相互作用，PMF被认为在宇宙微波背景（CMB）各向异性上留下了足迹。在本文中，我们研究了PMF在较小的尺度上如何影响CMB各向异性，而不是CMB光子的平均无路径。由于PMFS，我们用Lorentz力解决了Baryon Euler方程，并表明来自PMFS的向量型扰动诱导CMB各向异性的丝绸尺度低于$ \ ell> 3000 $。根据我们的计算，我们对普朗克和南极望远镜（SPT）获得的CMB温度各向异性的PMF构成了约束。我们发现，SPT 2017带有$ \ ell \ ell \ lyssim 8000 $的高度分辨率的温度各向异性偏爱PMF模型，其规模依赖性很小。结果，Planck和SPT的联合分析对PMF光谱指数的限制为$ N_B <-1.14 $在95％的置信度（C.L.）中，与仅Planck的约束$ n_b <-0.28 $相比，这更为严格。我们表明，在1 MPC量表上归一化的PMF强度也被严格限制为$ b_ {1 \ mathrm {mpc}}} <1.5 $ ng，与Planck和SPT一起在95％C.L.，而$ B_ {1 \ Mathrm {Mppc}}} <3.2 $ ng at planc <3.2 $ ng at planc c.当包括PMF引起的SPT数据和CMB各向异性时，我们还讨论了对宇宙参数估计的影响。
The primordial magnetic fields (PMFs) produced in the early universe are expected to be the origin of the large-scale cosmic magnetic fields. The PMFs are considered to leave a footprint on the cosmic microwave background (CMB) anisotropies due to both the electromagnetic force and gravitational interaction. In this paper, we investigate how the PMFs affect the CMB anisotropies on smaller scales than the mean-free-path of the CMB photons. We solve the baryon Euler equation with Lorentz force due to the PMFs, and we show that the vector-type perturbations from the PMFs induce the CMB anisotropies below the Silk scale as $\ell>3000$. Based on our calculations, we put a constraint on the PMFs from the combined CMB temperature anisotropies obtained by Planck and South Pole Telescope (SPT). We have found that the highly-resolved temperature anisotropies of the SPT 2017 bandpowers at $\ell \lesssim 8000$ favor the PMF model with a small scale-dependence. As a result, the Planck and SPT's joint-analysis puts a constraint on the PMF spectral index as $n_B<-1.14$ at 95% confidence level (C.L.), and this is more stringent compared with the Planck-only constraint $n_B<-0.28$. We show that the PMF strength normalized on the co-moving 1 Mpc scale is also tightly constrained as $B_{1\mathrm{Mpc}}<1.5$ nG with Planck and SPT at 95% C.L., while $B_{1\mathrm{Mpc}}<3.2$ nG only with the Planck data at 95% C.L. We also discuss the effects on the cosmological parameter estimate when including the SPT data and CMB anisotropies induced by the PMFs.
