Speaker
Description
Cosmic dust is a fundamentally important component of the interstellar medium, both for its impact on observable quantities and its dynamical influence on the ISM. Dust grains potentially mediate feedback mechanisms such as radiation pressure, multiple cooling and heating processes, and the coupling of neutral gas to magnetic fields. However, the importance and relative strengths of these effects are very uncertain, in large part because many basic questions about the origin, evolution, and properties of cosmic dust remain unanswered. Our group is addressing these questions by conducting a large program of molecular dynamics simulations of individual dust grains in which every atom is accounted for. These have enabled, for the first time, estimation of some grain physical processes rates (i.e. accretion, coagulation, shattering) from first principles. I will overview these results and discuss their implications for dust evolution in the interstellar medium. I will also present high-resolution simulations of kpc-scale ISM patches which include a novel model for the evolution of cosmic dust grains in a multiphase medium that incorporates the results of these molecular dynamics calculations. These simulations provide predictions for the dust chemical composition and size distribution in both local and high-redshift galaxies with unprecedented physical fidelity, therefore offering unique insight into the physics of feedback in the interstellar medium.
