测试冷核中辐射分解、非扩散化学和化学解吸的各种假设
Testing various assumptions for radiolysis, non-diffusive chemistry, and chemical desorption in cold cores
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中文总结 AI 辅助
研究星际气体和尘埃化学，通过在天体化学模型鹦鹉螺中添加辐射分解、非扩散化学和化学解吸机制并测试，比较预测与观测结果，发现各机制对气相和冰物种有不同影响，标准模型在气相丰度方面表现最佳，强调需更多实验约束相关效率。
中文摘要 AI 辅助
自20世纪80年代初以来，气相天体化学模型被开发用于研究星际气体和尘埃化学，90年代起出现气-尘模型。每个已发表模型都包含各种主要针对表面过程的假设。本文比较了最近添加的尘埃表面化学机制，即非扩散化学、辐射分解和化学解吸。将这些过程的几种形式主义添加到天体化学模型鹦鹉螺中并进行测试，比较预测的气相和冰丰度，并与观测到的气体和冰成分进行比较。主要发现包括：辐射分解本身不影响结果；非扩散化学会影响气相和冰物种，但取决于采用的形式主义；化学解吸的形式主义会使气相产生高达十倍的差异；标准模型在气相丰度方面产生的结果最佳。一些尘埃表面过程的形式主义对气相丰度也很重要，不过需要更多实验来约束其效率，化学解吸的每种形式主义都依赖一个不确定参数。
英文摘要
To study interstellar gas and grain chemistry, gas-phase astrochemical models have been developed since the early 1980s and gas-grain models since the 1990s. Each published model includes various assumptions mainly for surface processes. In this paper, we compare recently added mechanisms for grain surface chemistry, namely, non-diffusive chemistry, radiolysis, and chemical desorption. Several formalisms for these processes have been added to our astrochemical model Nautilus, and we tested them, comparing the predicted gas-phase and ice abundances. Our predictions are also compared to gas and ice observed compositions. Our main findings are that radiolysis itself does not influence the results. Non-diffusive chemistry can have an impact on the gas-phase and ice species, but it depends on the adopted formalism. In particular, the one of Shingledecker & Herbst (2018) changes the main reservoirs of the species in the ices, impacting the species in the gas-phase as well. The adopted formalism for chemical desorption can produce differences in the gas-phase by up to a factor of ten. Last, our standard model, without non-diffusive chemistry and with the chemical desorption from Fredon et al. (2021), produces the best results in relation to observed gas-phase abundances, while the ice observed agreement is unchanged. The formalism for some grain surface processes are important even for gas-phase abundances. More experiments are needed to constrain their efficiency, however. For the chemical desorption, each formalism relies on an uncertain parameter, which is the fraction of the energy actually delivered to the products, that can be adjusted to reproduce the experiments.
