Title: Did BICEP2 see vector modes? First B-mode constraints on cosmic defects Show Chinese title

Title: BICEP2看到了矢量模态吗？ 首次对宇宙缺陷的B模约束

Abstract: Scaling networks of cosmic defects, such as strings and textures, actively generate scalar, vector and tensor metric perturbations throughout the history of the universe. In particular, {\em vector} modes sourced by defects are an efficient source of the CMB B-mode polarization. We use the recently released BICEP2 and POLARBEAR B-mode polarization spectra to constrain properties of a wide range of different types of cosmic strings networks. We find that in order for strings to provide a satisfactory fit on their own, the effective inter-string distance needs to be extremely large -- spectra that fit the data best are more representative of global strings and textures. When a local string contribution is considered together with the inflationary B-mode spectrum, the fit is improved. We discuss implications of these results for theories that predict cosmic defects. Show Chinese abstract

Abstract: 宇宙缺陷网络，如弦和纹理，在宇宙的历史中主动产生标量、矢量和张量度规扰动。 特别是，由缺陷产生的{\em 向量}模式是CMB B模式极化的一个有效来源。 我们使用最近发布的BICEP2和POLARBEAR B模式极化谱来限制各种不同类型宇宙弦网络的特性。 我们发现，为了使弦自身提供令人满意的拟合，有效的弦间距离需要非常大——最佳拟合数据的谱更代表全局弦和纹理。 当考虑局部弦贡献与暴胀B模式谱一起时，拟合效果得到改善。 我们讨论这些结果对预测宇宙缺陷的理论的影响。