标题： 探测早期宇宙的膨胀引力波 显示英文标题

标题： Probing the early universe with inflationary gravitational waves

摘要： 接近共动波数 k 处，来自暴胀的引力波背景（GWB）携带着宇宙历史两个时刻的物理条件信息：k“离开视界”时的时刻和它“重新进入视界”后的时刻。 我们研究了如果通过大尺度宇宙微波背景（CMB）偏振实验与基于太空的小尺度激光干涉仪实验相结合来测量GWB，可以从其中提取多少信息。 为了分离这些信息，我们推导出一个新的引力波传递函数，该函数包含了先前处理中被处理得不够准确、不够普遍或者完全缺失的一些物理效应。 特别是，它包含了以下内容：(i) 随时间变化的暗能量状态方程 w(z)；(ii) 早期宇宙中由于自由流相对论粒子引起的张量各向异性应力；以及(iii) 引力辐射时代偏离标准状态方程 w=1/3 的各种物理效应。 基于这个传递函数，我们探讨了GWB在检验暴胀理论以及探测暴胀结束与电弱相变之间的“原初黑暗时代”方面的潜力。 显示英文摘要

摘要： Near comoving wavenumber k, the gravitational-wave background (GWB) from inflation carries information about the physical conditions near two moments in cosmic history: the moment when k ``left the horizon'' during inflation, and the moment when it ``re-entered the horizon'' after inflation. We investigate the extent to which this information can be extracted if the GWB is measured by a combination of cosmic-microwave-background (CMB) polarization experiments on large scales and space-based laser-interferometer experiments on small scales. To disentangle this information, we derive a new gravitational-wave transfer function that incorporates a number of physical effects that were treated less accurately, less generally, or were missing altogether in previous treatments. In particular, it incorporates: (i) dark energy with time-varying equation-of-state w(z); (ii) tensor anisotropic stress due to free-streaming relativistic particles in the early universe; and (iii) a variety of physical effects that cause deviations from the standard equation-of-state w=1/3 during the radiation era. Based on this transfer function, we consider the degree to which the GWB can be used to test inflation and to probe the ``primordial dark age'' between the end of inflation and the electroweak phase transition.