论文标题
宇宙电离期间Minihalos的光蒸发：原始和金属富集的光环
Photoevaporation of Minihalos during Cosmic Reionization: Primordial and Metal-Enriched Halos
论文作者
论文摘要
半乳酸间培养基的密度分布在宇宙电离研究中是一个不确定但非常重要的问题。预计早期宇宙中有低质量的“ Minihalos”托管的大量气云，它们充当光子下沉，直到新兴的超紫罗兰背景（UVB）辐射进行光蒸发。我们执行一套辐射流体动力学模拟，以研究Minihalos的光蒸发。我们的模拟遵循流体动力学，非平衡化学和相关的冷却过程，以自洽的方式进行。我们通过考虑多种气体金属性（$ 0 \，z_ \ odot \ odot \ leq z \ leq 10^{ - 3} \，z_ \ odot $），halo mass（$ 10^3 m_ \ odot \ odot \ odot \ leq mon \ leq 10^8 m_ \ odot $ j; \ leq 1 $），以及电离源的转交置（$ 10 \ leq z _ {\ rm in} \ leq 20 $）。我们表明，小光环在数百年中蒸发，而较大的质量晕圈持续了十倍。我们表明，Minihalo的气体质量演变可以以缩放参数为特征，该缩放参数是通过光环质量，背景辐射强度和红移的组合给出的。富含金属的光晕的有效辐射冷却可引起气体的快速冷凝，形成密集的自固定芯。在具有高金属度的光环中，冷，密集的芯在重力上可能变得不稳定。早期的金属富集可以允许在宇宙电离期间在Minihalos中形成恒星。
The density distribution of the inter-galactic medium is an uncertain but highly important issue in the study of cosmic reionization. It is expected that there are abundant gas clouds hosted by low-mass "minihalos" in the early universe, which act as photon sinks until photoevaporated by the emerging ultra-violet background (UVB) radiation. We perform a suite of radiation hydrodynamics simulations to study the photoevaporation of minihalos. Our simulations follow hydrodynamics, non-equilibrium chemistry, and the associated cooling processes in a self-consistent manner. We conduct a parametric study by considering a wide range of gas metallicity ($0\,Z_\odot \leq Z \leq 10^{-3}\,Z_\odot$), halo mass ($10^3 M_\odot \leq M \leq 10^8 M_\odot$), UVB intensity ($0.01 \leq J_{21} \leq 1$), and turn-on redshift of ionizing sources ($10\leq z_{\rm IN} \leq 20$). We show that small halos are evaporated in a few tens million years, whereas larger mass halos survive for ten times longer. We show that the gas mass evolution of a minihalo can be characterized by a scaling parameter that is given by a combination of the halo mass, background radiation intensity, and redshift. Efficient radiative cooling in metal-enriched halos induces fast condensation of the gas to form a dense, self-shielded core. The cold, dense core can become gravitationally unstable in halos with high metallicities. Early metal enrichment may allow star formation in minihalos during cosmic reionization.
