We present numerical relativity simulations of cosmological scenarios in which the universe is smoothed and flattened by undergoing a phase of slow contraction and test their sensitivity to a wide range of initial conditions. Our numerical scheme enables the variation of all freely specifiable physical quantities that characterize the initial spatial hypersurface, such as the initial shear and spatial curvature contributions as well as the initial field and velocity distributions of the scalar that drives the cosmological evolution. In particular, we include initial conditions that are far outside the perturbative regime of the well-known attractor scaling solution. We complement our numerical results by analytically performing a complete dynamical systems analysis and show that the two approaches yield consistent results.

中文翻译：

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缓慢收缩对宇宙初始条件的鲁棒性

我们展示了宇宙学场景的数值相对论模拟，其中宇宙通过经历一个缓慢收缩阶段而变得平滑和扁平，并测试它们对各种初始条件的敏感性。我们的数值方案使表征初始空间超曲面的所有可自由指定的物理量发生变化，例如初始剪切和空间曲率贡献以及驱动宇宙演化的标量的初始场和​​速度分布。特别是，我们包括了远远超出众所周知的吸引子缩放解决方案的微扰机制的初始条件。我们通过分析执行完整的动力系统分析来补充我们的数值结果，并表明这两种方法产生一致的结果。