Cosmic Dust Aggregation with Stochastic Charging

TL;DR

This paper models how stochastic fluctuations in the electrical charge of cosmic dust grains influence their aggregation process and resulting physical characteristics in astrophysical environments.

Contribution

It introduces a set of stochastic differential equations to simulate charge fluctuations on irregular dust aggregates and examines their impact on coagulation.

Findings

Small dust charges significantly affect coagulation dynamics.

Charge fluctuations alter aggregate physical properties.

Electrostatic forces influence dust aggregation rates.

Abstract

The coagulation of cosmic dust grains is a fundamental process which takes place in astrophysical environments, such as presolar nebulae and circumstellar and protoplanetary disks. Cosmic dust grains can become charged through interaction with their plasma environment or other processes, and the resultant electrostatic force between dust grains can strongly affect their coagulation rate. Since ions and electrons are collected on the surface of the dust grain at random time intervals, the electrical charge of a dust grain experiences stochastic fluctuations. In this study, a set of stochastic differential equations is developed to model these fluctuations over the surface of an irregularly-shaped aggregate. Then, employing the data produced, the influence of the charge fluctuations on the coagulation process and the physical characteristics of the aggregates formed is examined. It is shown that dust with small charges (due to the small size of the dust grains or a tenuous plasma environment) are affected most strongly.