论文标题
$ {\ rm h_2} $ hi-shielding in UV-Irradiated Protogalaxies：抑制光解离速率
HI-shielding of ${\rm H_2}$ in UV-irradiated protogalaxies: suppression of the photodissociation rate
论文作者
论文摘要
我们研究了中性氢吸收对$ {\ rm H_2} $ potodissociation $ {\ rm h_2}的影响，暴露于软紫外辐射。 Lyman系列的吸收可能会大大耗尽分离光子，因为与$ {\ rm H_2} $ lyman-werner频带的线重叠，中性柱密度超过$ 10^{22} $ $ {\ rm cm^{ - 2}} $，但此效果以前尚未在protog necact中使用。我们使用高分辨率的三维流体动力模拟来研究这种“屏蔽”在三个无金属的原子冷却光环中，在Redshift $ Z \ SIM 10-20 $上崩溃。我们使用Cloudy Modeling更新以前的拟合公式以进行HI-Shielfing，这是屏蔽非地面状态$ {\ rm H_2} $ ROVIBLATICATY群体的更好模型，并在我们的模拟中实现了新拟合。我们发现，HI-Shielding的包含增加了“关键通量”，以抑制这些光环中的$ {\ rm H_2} $冷却$ \ sim 60-100 $ $。较大的关键通量具有尤其是预测的候选光环数量，其中“直接崩溃”可以大量种子（$ \ sim 10^5 $ $ {\ rm m_ \ odot} $）在$ z \ sim 15 $上。
We study the impact of neutral hydrogen absorption on ${\rm H_2}$ photodissociation in protogalactic haloes exposed to soft-UV radiation. Lyman-series absorption can significantly deplete dissociating photons as line overlap with the ${\rm H_2}$ Lyman-Werner bands occurs for neutral column densities exceeding $10^{22}$ ${\rm cm^{-2}}$, but this effect has not been previously included in studies of protogalactic haloes. We use high-resolution three-dimensional hydrodynamic simulations to investigate this "HI-shielding" in three metal-free atomic cooling haloes collapsing at redshift $z \sim 10-20$. We use CLOUDY modeling to update a previous fitting formula for HI-shielding which is a better model for shielding of non-ground state ${\rm H_2}$ rovibrational populations and implement the new fit in our simulations. We find that the inclusion of HI-shielding increases the "critical flux" for suppression of ${\rm H_2}$ cooling in these haloes by $\sim 60-100$ per cent. The larger critical flux has implications in particular for the predicted numbers of candidate haloes in which "direct collapse" could seed massive ($\sim 10^5$ ${\rm M_\odot}$) black holes at $z \sim 15$.
