[论文解读] The FLAMINGO project: Baryon effects on the matter power spectrum

Matthieu Schaller, Joop Schaye+3 more|arXiv (Cornell University)|Oct 22, 2024

Particle physics theoretical and experimental studies被引用 6

一句话总结

本文使用 Flamingo 水动力学模拟套件来建模重子对物质分布函数的影响，以及建立高斯过程仿真器来在不同的红移和校准情景下预测这些效应，并在与模拟结果在 k ~ 10 h/Mpc 和 z ≤ 2 的范围内验证其准确性。

ABSTRACT

The effect of baryon physics associated with galaxy formation onto the large-scale matter distribution of the Universe is a key uncertainty in the theoretical modelling required for the interpretation of Stage IV surveys. We use the FLAMINGO simulations to study the baryon response due to galaxy formation of the total matter power spectrum. We find that it is only well converged for simulation volumes in excess of $200^3$ Mpc$^3$. We report results for simulations of varying feedback intensity, which either match the X-ray inferred gas fractions in clusters and the $z=0$ stellar mass function, or shifted versions of the data, as well as for different implementations of AGN feedback. We package our results in the form of a Gaussian process emulator which can rapidly reproduce all the simulations' predictions to better than one per cent up to the comoving wavenumber $k = 10~h$ Mpc$^{-1}$ and up to $z=3$ for all the feedback models present in the FLAMINGO suite. We find that the response becomes stronger, the range of scales affected increases, and the position of the minimum of the response moves to smaller scales as the redshift decreases. We find that lower gas fractions in groups and clusters lead to a stronger response and that the use of collimated jets instead of thermally driven winds for AGN feedback enhances the effect. Lowering the stellar masses at fixed cluster gas fractions also increases the magnitude of the response. We find only a small (1% at $k<10~h$ Mpc$^{-1}$) dependence of our results on the background cosmology, but a wider range of cosmology variations will be needed to confirm this result. The response we obtain for our strongest feedback models is compatible with some of the recent analyses combining weak lensing with external data. Such a response is, however, in strong tension with the X-ray inferred gas fractions in clusters used to calibrate the FLAMINGO model.

研究动机与目标

• 量化星系形成中的重子物理如何在不同尺度和红移下改变总物质幂谱。
• 使用仿真器将一个灵活的模拟套件校准为观测到的群组与团簇气体分数。
• 提供一个快速、公开可用的工具，将重子效应纳入 Stage IV 调查的宇宙学分析。

提出的方法

• 运行 Flamingo 水动力学模拟，变动气体分数、恒星质量和 AGN 反馈实现。
• 在多个红移下测量总物质幂谱及其与仅暗物质跑的比值。
• 构建一个高斯过程仿真器，在五个红移、31 个 k-箱预测重子响应 R(k)=P(k)/PDMO(k)。
• 在九个仿真组成的拉丁超立方设计上训练仿真器，并在额外的运行中进行验证。
• 证明仿真器能够在 k=10 h/Mpc 和 z≤2 的范围内以低于百分比级别的精度重现仿真。

实验结果

研究问题

• RQ1 在尺度 (k) 和红移 (z) 下，重子引起的物质幂谱修改有多强？
• RQ2 气体分数、恒星质量以及 AGN 反馈模式的变化如何影响重子响应？
• RQ3 高斯过程仿真器能否在 Flamingo 模型变体之间可靠重现幂谱响应，以用于快速宇宙学推断？

主要发现

• 重子响应的收敛性需要体积超过 200^3 Mpc^3 的模拟才能在 z=0 和 z=1 处达到 ~1% 的精度，直至 k~10 h/Mpc。
• 随着红移减小，重子响应增强、尺度变窄并将最小值向更小的尺度移动。
• 群组与簇中的气体分数降低会放大重子响应；与热反馈相比，定流喷射型 AGN 反馈进一步增强该效应。
• 在固定气体分数下，恒星质量的降低会增加响应幅度；在所探讨的变化范围内，宇宙学对 k<10 h/Mpc 的影响仅约 ~1%。
• 最强反馈的仿真器预测与某些弱透镜分析结果相符，但与用于 Flamingo 校准的 X 射线推断的群簇气体分数存在冲突。
• 作者提供一个公开的仿真器（FlamingoBaryonResponseEmulator），在 k<10 h/Mpc、直至 z=2 的范围内预测 R(k) 的精度≤1%，并可与 PDMO 或 Boltzmann 求解器集成。