Liu Jing, Cai Rong-Gen, Guo Zong-Kuan
School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
School of Physical Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China.
Phys Rev Lett. 2021 Apr 9;126(14):141303. doi: 10.1103/PhysRevLett.126.141303.
We investigate the stochastic gravitational wave background (SGWB) from cosmic domain walls (DWs) caused by quantum fluctuations of a light scalar field ϕ during inflation. Large-scale perturbations of ϕ lead to large-scale perturbations of DW energy density and anisotropies in the SGWB. We find that the angular power spectrum of this SGWB is scale invariant and at least of the order of 10^{-2}, which is a distinctive feature of observational interest. Since we have not detected primordial gravitational waves yet, anisotropies of the SGWB provide a nontrivial opportunity to verify the rationality of inflation and detect the energy scale of inflation, especially for low-scale inflationary models. Square kilometer array has the opportunity to detect the anisotropies of such SGWBs. The common-spectrum process observed recently by NANOGrav could also be interpreted by the SGWB from cosmic DWs.
我们研究了在暴胀期间由轻标量场ϕ的量子涨落引起的宇宙畴壁（DWs）产生的随机引力波背景（SGWB）。ϕ的大规模扰动会导致DW能量密度的大规模扰动以及SGWB中的各向异性。我们发现，这种SGWB的角功率谱是标度不变的，且至少为10^-2量级，这是一个具有观测意义的显著特征。由于我们尚未探测到原初引力波，SGWB的各向异性为验证暴胀的合理性以及探测暴胀的能量尺度提供了一个重要契机，特别是对于低尺度暴胀模型而言。平方公里阵列有机会探测到此类SGWB的各向异性。NANOGrav最近观测到的共谱过程也可以由宇宙DWs产生的SGWB来解释。
