论文标题
假设电离平衡和对Lyman-$ \Mathrmα$森林功率谱的影响在电离结束时，$ 8 \ geq Z \ geq 5 $
Assuming Ionization Equilibrium and the Impact on the Lyman-$\mathrmα$ Forest Power Spectrum during the End of Reionization at $8 \geq z \geq 5$
论文作者
论文摘要
我们探讨了使用宇宙辐射流体动力学\ textsc {Technicolor Dawn}模拟在氢气时期结束时，电离平衡的假设如何调节建模的层间培养基（IgM）。在中性和部分离子化的区域中，元层紫外线背景（UVB）很弱，电离时间表$ t_ \ mathrm {ion} \equivγ^{ - 1} $超过了哈勃时间。假设在此类区域中的光电离平衡会人为地提高电离速率，从而加速电离。相比之下，重组时间$ t_ \ mathrm {rec} <t_ \ mathrm {ion} $在光电离区域中，结果假设光电离平衡人为地增加了中性氢的分数。使用$ 8 \ geq z \ geq 5 $之间的快照，我们将预测的lyman- $α$ forest通量功率谱频谱与有和不假定电离平衡相比。小尺度（$ k> 0.1 $ rad s km $^{ - 1} $）在电离平衡案例中的$ 7 \ leq Z \ leq 5.5 $显示出降低的功率，而较大的尺度不受影响。出于相同的原因而发生这种情况：电离平衡人为地抑制自屏蔽气体中的中性分数，并在空隙中增强电离，从而抑制了电离场中的小规模波动。当体积平均的中性分数下降到$ 10^{-4} $以下时，Lyman-$α$ Forest（LAF）上非平衡电离的签名消失了。与最近的观察结果相比表明，在LAF通量功率谱中，这些非平衡效应尚不可观察到。
We explore how the assumption of ionization equilibrium modulates the modeled intergalactic medium (IGM) at the end of the hydrogen Epoch of Reionization using the cosmological radiation hydrodynamic \textsc{Technicolor Dawn} simulation. In neutral and partially-ionized regions where the metagalactic ultraviolet background (UVB) is weak, the ionization timescale $t_\mathrm{ion}\equiv Γ^{-1}$ exceeds the Hubble time. Assuming photoionization equilibrium in such regions artificially boosts the ionization rate, accelerating reionization. By contrast, the recombination time $t_\mathrm{rec} < t_\mathrm{ion}$ in photoionized regions, with the result that assuming photoionization equilibrium artificially increases the neutral hydrogen fraction. Using snapshots between $8 \geq z \geq 5$, we compare the predicted Lyman-$α$ forest flux power spectrum with and without the assumption of ionization equilibrium. Small scales ($k > 0.1$ rad s km$^{-1}$) exhibit reduced power from $7 \leq z \leq 5.5$ in the ionization equilibrium case while larger scales are unaffected. This occurs for the same reasons: ionization equilibrium artificially suppresses the neutral fraction in self-shielded gas and boosts ionizations in voids, suppressing small-scale fluctuations in the ionization field. When the volume-averaged neutral fraction drops below $10^{-4}$, the signature of non-equilibrium ionizations on the Lyman-$α$ forest (LAF) disappears. Comparing with recent observations indicates that these non-equilibrium effects are not yet observable in the LAF flux power spectrum.
