标题： 前恒星核心中复杂有机分子的形成：非扩散性尘粒化学的作用 显示英文标题

标题： Formation of Complex Organic Molecules in Prestellar Cores: The Role of Non-Diffusive Grain Chemistry

摘要： 我们展示了对预恒星核L1544的冰和气体中复杂有机分子(COMs)的天体化学建模结果，使用的是最近更新的基于MONACO速率方程的模型。该模型特别包括非扩散过程、乙醛和甲烷冰形成的新的实验室验证的化学路径，以及H和$\rm H_2$脱附能根据$\rm H_2$分子的表面覆盖度变化的情况。首次，我们同时再现了气相中几种含氧COMs的丰度、甲醇发射峰的大致位置，以及L1544冰壳中甲醇的丰度。在颗粒表面，诸如$\rm CH_3$、$\rm CH_3O$和$\rm HCO$等物种之间的自由基-自由基反应高效地非扩散进行。通过H加成/抽提表面反应循环放大的化学脱附，COMs被输送到气相。然而，气相中的化学反应也对气相中COMs的形成有显著贡献，但不涉及COMs固态丰度。 这特别适用于CH$_3$CHO和CH$_3$OCH$_3$。 模拟冰中复杂有机分子的丰度范围为1%--2%（对于甲酸甲酯冰），或$\sim$~0.1%（对于CH$_3$CHO和CH$_3$OCH$_3$），相对于H$_2$O冰的丰度。我们强调L1544中冰态复杂有机分子的模拟丰度与热核/热辉核气体相中复杂有机分子的丰度之间的相似性。我们将非扩散模型与扩散模型进行比较，并提供了物种扩散能与脱附能比值的限制。 显示英文摘要

摘要： We present the results of astrochemical modeling of complex organic molecules (COMs) in the ice and gas of the prestellar core L1544 with the recently updated MONACO rate equations-based model. The model includes, in particular, non-diffusive processes, new laboratory verified chemical routes for acetaldehyde and methane ice formation and variation of H and $\rm H_2$ desorption energies depending on the surface coverage by $\rm H_2$ molecules. For the first time, we simultaneously reproduce the abundances of several oxygen-bearing COMs in the gas phase, the approximate location of the peak of methanol emission, as well as the abundance of methanol in the icy mantles of L1544. Radical-radical reactions on grains surface between species such as $\rm CH_3$, $\rm CH_3O$ and $\rm HCO$ efficiently proceed non-diffusively. COMs are delivered to the gas phase via chemical desorption amplified by the loops of H-addition/abstraction surface reactions. However, gas-phase chemical reactions as well provide a noticeable input to the formation of COMs in the gas, but not to the COMs solid-state abundances. This particularly applies for CH$_3$CHO and CH$_3$OCH$_3$. The simulated abundances of COMs in the ice are in the range 1\%--2\% (for methyl formate ice) or $\sim$~0.1\% (for CH$_3$CHO and CH$_3$OCH$_3$) with respect to the abundance of H$_2$O ice. We stress a similarity between the simulated abundances of icy COMs in L1544 and the abundances of COMs in the gas phase of hot cores/corinos. We compare our non-diffusive model with the diffusive model and provide constraints for the species' diffusion-to-desorption energy ratios.