In a broad class of scenarios, inflation is followed by an extended era of matter-dominated expansion during which the inflaton condensate is nonrelativistic on subhorizon scales. During this phase density perturbations grow to the point of nonlinearity and collapse into bound structures. This epoch strongly resembles structure formation with ultra-light axion-like particles. This parallel permits us to adapt results from studies of cosmological structure formation to describe the nonlinear dynamics of this post-inflationary epoch. We show that the inflaton condensate fragments into "inflaton clusters", analogues of axion dark matter halos in present-day cosmology. Moreover, solitonic objects or "inflaton stars" can form inside these clusters, leading to density contrasts as large as $10^6$ in the post-inflationary universe.

中文翻译：

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暴胀子星团和暴胀子星

在一大类场景中，暴胀之后是物质主导膨胀的延长时代，在此期间暴胀凝聚物在亚地平线尺度上是非相对论的。在此阶段，密度扰动增长到非线性点并坍塌成束缚结构。这个时代非常类似于超轻轴子状粒子的结构形成。这种平行使我们能够改编宇宙结构形成研究的结果来描述这个后通货膨胀时代的非线性动力学。我们展示了暴胀子将碎片凝聚成“暴胀子星团”，类似于当今宇宙学中的轴子暗物质晕。此外，孤子物体或“暴胀星”可以在这些星团内部形成，导致暴胀后宇宙中的密度差异高达 $10^6$。