AI 中文总结
该研究介绍了DESTINY天体化学框架，能纳入结合能分布并考虑表面过程竞争，通过分支吸收马尔可夫链等方法重新表述表面过程，与Nautilus基准测试，结果显示其能改变颗粒表面化学，未来有望扩展。
AI 中文摘要
在低温星际条件下，星际冰的无定形结构导致每个物种的结合能分布（BEDs）。然而，只有少数研究尝试将其纳入天体化学模型。本文介绍了命运（DESTINY），这是一个确定性天体化学框架，旨在纳入BEDs，同时自洽地考虑活化表面过程之间的竞争。该框架目前限于单层。由表面物种引发的表面过程使用通过分支吸收马尔可夫链表示的试验频率上限形式重新表述。基于归一化有效概率重新定义常微分方程（ODE）系统。讨论了基于简化表面网络的初步结果。为了将概率重新表述的影响与BED离散化引起的影响隔离开来，命运（DESTINY）与基于单BE速率方程的开源代码鹦鹉螺（Nautilus）进行了基准测试。在单BE极限下，命运（DESTINY）对大多数物种再现了鹦鹉螺（Nautilus）的行为。对于CH$_{x = [2,4]}$获得了最大偏差；这些偏差可追溯到对H$_2$碰撞效应的不同处理，这影响了命运（DESTINY）框架内的H$_2$表面探索和解吸效率。引入BEDs会在不同深度的吸附位点之间重新分配物种，改变扩散、解吸和反应之间的平衡。对于H、H$_2$、NH$_x$、NO、CH$_x$、CO和H$_x$CO发现了显著影响。初步结果表明，对H$_2$碰撞效应的自洽处理与对BEDs的明确处理可以显著改变颗粒表面化学。预计在不久的将来会有进一步的框架扩展。
英文摘要
Under cryogenic interstellar conditions, the amorphous structure of interstellar ice results in binding-energy distributions (BEDs) per species. However, only few studies attempted their inclusion in astrochemical models. This paper introduces DESTINY, a deterministic astrochemical framework designed to incorporate BEDs while self-consistently accounting for the competition among activated surface processes. The framework is currently constrained to a monolayer. Surface processes initiated by surface species are reformulated using a trial-frequency-capped formalism represented through branched absorbing Markov chains. The ordinary differential equations (ODE) system is redefined based on normalized effective probabilities. Preliminary results based on a reduced surface network are discussed. To isolate the effects of the probabilistic reformulation from those induced by BED discretizations, DESTINY is benchmarked against Nautilus, a single-BE rate-equation based open source code. In the single-BE limit, DESTINY reproduces the behavior of Nautilus for most species. The largest deviations are obtained for CH$_{x = [2,4]}$ ; these are traced to a different treatment of the H$_2$ encounter effect, impacting both H$_2$ surface exploration and desorption efficiencies within the DESTINY framework. Introducing BEDs redistributes species among adsorption sites of different depths, altering the balance between diffusion, desorption, and reactions. Significant effects are found for H, H$_2$, NH$_x$, NO, CH$_x$, CO and H$_x$CO. Preliminary results showed that the self-consistent treatment of the H$_2$ encounter effect coupled with the explicit treatment of BEDs can substantially modify grain-surface chemistry. Further framework extensions are expected in the near future.
CommentsAccepted for publication in A&A, Sect. 6. Interstellar and circumstellar matter. 24 pages, 15 Figures
