%0 Generic %1 zeng2020nonequilibrium %A Zeng, Chenxiao %A Hirata, Christopher M. %D 2020 %K library %T Non-equilibrium temperature evolution of ionization fronts during the Epoch of Reionization %U http://arxiv.org/abs/2007.02940 %X 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 $T_re$. 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 ($łessapprox\ 10^9~cm/s$), but deviations from equilibrium occur for faster fronts. The post-front temperature $T_re$ is lower by up to 19.7\% (at $310^9$ cm/s) or 30.8\% (at $10^10$ cm/s) relative to the equilibrium case.

@misc{zeng2020nonequilibrium, abstract = {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.}, added-at = {2020-07-08T07:26:17.000+0200}, author = {Zeng, Chenxiao and Hirata, Christopher M.}, biburl = {https://www.bibsonomy.org/bibtex/261180ce7f23888e3ccdffd1b108a1f84/gpkulkarni}, description = {Non-equilibrium temperature evolution of ionization fronts during the Epoch of Reionization}, interhash = {942381d66867e062acf9700b0a93686c}, intrahash = {61180ce7f23888e3ccdffd1b108a1f84}, keywords = {library}, note = {cite arxiv:2007.02940Comment: 9 pages, 6 figures}, timestamp = {2020-07-08T07:26:17.000+0200}, title = {Non-equilibrium temperature evolution of ionization fronts during the Epoch of Reionization}, url = {http://arxiv.org/abs/2007.02940}, year = 2020 }