广义立方协变伽利略模型中大规模结构的N体模拟
N-body Simulations of Large-Scale Structure in the Generalized Cubic Covariant Galileon Model
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中文总结 AI 辅助
本文通过ECOSMOG代码实现GCCG模型的非线性标量场方程，开展首次相关N体模拟，量化其对非线性物质功率谱和暗物质晕丰度的影响，确定半解析预测的有效范围。
中文摘要 AI 辅助
我们开展了广义立方协变伽利略（Generalized Cubic Covariant Galileon，GCCG）模型中结构形成的首次N体模拟。该理论通过幂律动力学与立方导数相互作用扩展了立方协变伽利略模型，且存在示踪解可导致晚期宇宙加速。此前对GCCG的研究多聚焦于背景、线性扰动或半解析非线性方案。本文在ECOSMOG自适应网格细化代码中实现了非线性标量场方程，使我们能追踪完全非线性区域内物质成团与Vainshtein屏蔽的耦合演化。我们量化了GCCG对非线性物质功率谱的影响，并将模拟结果与晕模型反应方法的预测进行对比。在所考虑的参数选择下，GCCG模型相较于对应的QCDM宇宙学模型增强了物质功率谱，该效应随红移降低而增大，在z=0的非线性过渡区域达到约7%；在更小尺度上，增强效应因Vainshtein屏蔽而减弱。我们发现反应框架能捕捉模拟的定性行为，但在深非线性尺度上存在残余差异。我们还分析了暗物质晕的丰度，发现其相较于QCDM的增强效应随红移降低而更显著，且在大质量端更为突出。这些模拟为GCCG中结构形成提供了首次非线性校准，并确定了高效半解析预测在即将开展的大规模结构巡天应用中的有效范围。
英文摘要
We present the first N-body simulations of structure formation in the Generalized Cubic Covariant Galileon (GCCG) model. This theory extends the cubic covariant Galileon through power-law kinetic and cubic derivative interactions and admits tracker solutions leading to late-time cosmic acceleration. Previous studies of GCCG have mostly focused on the background, linear perturbations, or semi-analytic nonlinear prescriptions. Here we implement the nonlinear scalar-field equation in the ECOSMOG adaptive-mesh refinement code, allowing us to follow the coupled evolution of matter clustering and Vainshtein screening in the fully nonlinear regime. We quantify the impact of GCCG on the nonlinear matter power spectrum and compare the simulation results with predictions from the halo-model reaction approach. For the parameter choices considered, the GCCG model enhances the matter power spectrum relative to the corresponding QCDM cosmology, with the effect increasing towards low redshift and reaching approximately $7\%$ at $z=0$ in the transition to the nonlinear regime. At smaller scales, the enhancement decreases as a consequence of Vainshtein screening. We find that the reaction framework captures the qualitative behaviour of the simulations, while residual differences appear on deeply nonlinear scales. We also analyse the abundance of dark matter haloes, finding an enhancement relative to QCDM that becomes more pronounced towards lower redshift and in the high-mass tail. These simulations provide the first nonlinear calibration of structure formation in GCCG and establish the range of validity of efficient semi-analytical predictions for applications to forthcoming large-scale-structure surveys.
