Simulation of the Formation and Morphology of Ice Mantles on Interstellar Grains

TL;DR

This paper uses Monte Carlo simulations to model the formation and morphology of ice mantles on interstellar grains, revealing how physical conditions influence ice growth and structure.

Contribution

It introduces a stochastic simulation approach to study ice mantle formation and provides the first images of interstellar ice morphology under various conditions.

Findings

Ice mantles grow only in denser regions.

Simulation reproduces observed ice formation patterns.

Morphology depends on physical parameters.

Abstract

Although still poorly understood, the chemistry that occurs on the surfaces of interstellar dust particles profoundly affects the growth of molecules in the interstellar medium. An important set of surface reactions produces icy mantles of many monolayers in cold and dense regions. The monolayers are dominated by water ice, but also contain CO, CO_{2}, and occasionally methanol as well as minor constituents. In this paper, the rate of production of water-ice dominated mantles is calculated for different physical conditions of interstellar clouds and for the first time images of the morphology of interstellar ices are presented. For this purpose, the continuous-time random-walk Monte Carlo simulation technique has been used. The visual extinction, density, and gas and grain temperatures are varied. It is shown that our stochastic approach can reproduce the important observation that ice mantles only grow in the denser regions.