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arXiv 2303.07503astro-ph.COgr-qc
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非对称暴胀势中预热导致的振荡子形成

Oscillon formation from preheating in asymmetric inflationary potentials

Rafid Mahbub, Swagat S. Mishra

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AI总结：

本文结合小振幅解析与 CosmoLattice 格点模拟，证明 α-attractor E-model 预热阶段可形成占总能量密度逾40%的振荡子。

摘要：

我们研究了在非对称暴胀势的预热阶段形成振荡子的可能性。我们利用小振幅分析，在解析上确立了形如 $V(ϕ)=\frac{1}{2}ϕ^2+Aϕ^3+Bϕ^4$ 的多项式势中 Klein-Gordon 方程存在类振荡子解；当 $ϕ\ll M_\text{pl}$ 且 $α\sim\mathcal{O}(1)$ 时，该势自然作为 α-attractor E-model 的 Taylor 展开出现。我们使用公开可用的格点模拟代码 $\mathcal{C}\text{osmo}\mathcal{L}\text{attice}$，对参数范围 $10^{-5}\lesssimα\lesssim 5\times10^{-4}$ 下 α-attractor E-model 中非线性结构的形成进行了详细数值分析。我们发现，对于 $α\lesssim2\times10^{-4}$，场涨落对均匀暴胀子凝聚体演化的反作用十分显著；在此情况下，我们观察到平均状态方程 $w\simeq0$ 的高度非线性结构形成。这些非线性结构可被解释为振荡子，证明它们能够在暴胀子围绕非对称势振荡期间形成；并且在我们整个模拟运行期间均存在，占总能量密度的 $\gtrsim40\\%$。

英文摘要：

We investigate the possibility of oscillon formation during the preheating phase of asymmetric inflationary potentials. We analytically establish the existence of oscillon-like solutions for the Klein-Gordon equation for a polynomial potential of the form $V(ϕ)=\frac{1}{2}ϕ^2+Aϕ^3+Bϕ^4$ using the small amplitude analysis, which naturally arises as a Taylor expansion of the $α$-attractor E-model for $ϕ\ll M_\text{pl}$ and $α\sim\mathcal{O}(1)$. We perform a detailed numerical analysis to study the formation of nonlinear structures in the $α$-attractor E-model using the publicly available lattice simulation code $\mathcal{C}\text{osmo}\mathcal{L}\text{attice}$ for parameters in the range $10^{-5}\lesssimα\lesssim 5\times 10^{-4}$. We find the backreaction of the field fluctuations onto the evolution of the homogeneous inflaton condensate to be significant for $α\lesssim 2\times 10^{-4}$ for which we observe the formation of highly nonlinear structures with average equation of state $w\simeq 0$. These nonlinear structures maybe interpreted as oscillons, providing evidence that they can form during the inflaton oscillations around an asymmetric potential and are found to be present for the entirety of the runtime of our simulations, comprising $\gtrsim 40\%$ of the total energy density.

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