基于半解析星系形成模型对再电离的稳健莱曼α森林约束
Robust Ly$α$ forest constraints on reionization from semi-analytic galaxy formation models
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中文总结 AI 辅助
研究利用半解析星系形成模型Meraxes，通过构建多种源模型并校准，测试莱曼α森林推断的再电离历史的稳健性，结果表明该历史对多种因素稳健，恢复出晚期且延长的再电离时期。
中文摘要 AI 辅助
高红移莱曼α森林是再电离最后阶段最灵敏的探测器之一，但其解读取决于电离源的建模方式。我们使用Meraxes这个半解析星系形成和再电离模型，应用于(210h⁻¹cMpc)³的宇宙学体积，并带有降至原子冷却阈值的合并树，来测试从莱曼α森林推断出的再电离历史的稳健性。我们构建了一组源模型，其中星系逃逸率fesc^gal作为晕质量、恒星质量、恒星形成率、特定恒星形成率或恒星形成盘表面密度的函数进行参数化。我们还考虑了吸积黑洞贡献电离光子或致密星系际气体进一步衰减电离光子逃逸的模型。每个模型都根据XQR - 30 +观测到的莱曼α有效光学深度分布进行校准。这些设定在晕质量和紫外光度之间重新分配逃逸光子预算，在固定晕质量下引入fesc^gal的散射，并允许再电离早期演化有适度变化。然而，所有可行的校准模型都恢复了一个晚期且延长的再电离时期，中点出现在z ∼ 6.2 - 6.9，最后阶段在z ∼ 5.36 - 5.57。我们的结果表明，从莱曼α森林推断出的晚期再电离历史对于星系 - 晕连接中基于物理的散射、适度的AGN贡献和唯象的CGM衰减是稳健的。
英文摘要
The high-redshift Ly$α$ forest provides one of the most sensitive probes of the final stages of reionization, but its interpretation can depend on how the ionizing sources are modelled. We test the robustness of Ly$α$ forest-inferred reionization histories using Meraxes, a semi-analytic model of galaxy formation and reionization applied to a cosmological volume of $(210h^{-1}{\rm cMpc})^3$ with merger trees augmented down to the atomic-cooling threshold. We construct a suite of source models in which the galaxy escape fraction, $f_{\rm esc}^{\rm gal}$, is parameterized as a function of halo mass, stellar mass, star formation rate, specific star formation rate, or star-forming disc surface density. We also consider models in which accreting blackholes contribute ionizing photons, or dense circumgalactic gas further attenuates the escape of ionizing photons. Each model is calibrated to the observed distribution of Ly$α$ effective optical depths from XQR-30+. These prescriptions redistribute the escaping photon budget across halo mass and UV luminosity, introduce scatter in $f_{\rm esc}^{\rm gal}$ at fixed halo mass, and allow modest variation in the early evolution of reionization. Nevertheless, all viable calibrated models recover a late and extended EoR, with the midpoint occurring at $z\sim6.2$--6.9 and the final stages at $z\sim5.36$--5.57. Our results indicate that the late reionization history inferred from Ly$α$ forest is robust to physically motivated scatter in the galaxy--halo connection, modest AGN contributions, and phenomenological CGM attenuation.
