论文标题
电离时期电离前沿的非平衡温度演变
Non-equilibrium temperature evolution of ionization fronts during the Epoch of Reionization
论文作者
论文摘要
电离时代（EOR）标志着宇宙黎明的末端和宇宙中大规模结构形成的开始。冲动的电离前线（I-Fronts）热量并在静脉间培养基（IGM）中的电离气泡内电离气体。在此过程中的温度是当前模型中的关键但不确定的成分。通常，电离模拟假设所有重子物种在I-Front的通过期间彼此瞬间热平衡。在这里，我们通过研究非平衡效应来提出一个新的电离界温度演化模型。特别是，我们包括主要的重子物种（$ e^{ - } $，\ hi，\ hii，\ hei和\ heii）之间的能量转移，并研究了它们对后离世前温度$ t _ {\ mathrm {re}} $的影响。为了在求解刚性方程时进行更好的步进尺寸控制，我们实现了隐式方法并构建能量传递速率矩阵。我们发现平衡的假设对于低速电离前端有效（$ \ Lessapprox \ 10^9〜 \ Mathrm {cm}/\ mathrm {s} $），但是与平衡的偏差相对于快速前部而发生。前温度$ t _ {\ mathrm {re}} $降低了19.7 \％（$ 3 \ times 10^9 $ cm/s）或30.8 \％（$ 10^{10} $ cm/s）相对于平衡情况。
The epoch of reionization (EoR) marks the end of the Cosmic Dawn and the beginning of large-scale structure formation in the universe. The impulsive ionization fronts (I-fronts) heat and ionize the gas within the reionization bubbles in the intergalactic medium (IGM). The temperature during this process is a key yet uncertain ingredient in current models. Typically, reionization simulations assume that all baryonic species are in instantaneous thermal equilibrium with each other during the passage of an I-front. Here we present a new model of the temperature evolution for the ionization front by studying non-equilibrium effects. In particular, we include the energy transfer between major baryon species ($e^{-}$, \HI, \HII, \HeI, and \HeII) and investigate their impacts on the post-ionization front temperature $T_{\mathrm{re}}$. For a better step-size control when solving the stiff equations, we implement an implicit method and construct an energy transfer rate matrix. We find that the assumption of equilibration is valid for a low-speed ionization front ($\lessapprox\ 10^9~\mathrm{cm}/\mathrm{s}$), but deviations from equilibrium occur for faster fronts. The post-front temperature $T_{\mathrm{re}}$ is lower by up to 19.7\% (at $3\times 10^9$ cm/s) or 30.8\% (at $10^{10}$ cm/s) relative to the equilibrium case.
