A new Monte Carlo code to simulate collisions between porous dust aggregates

PLANES, MARÍA BELÉN

virtual

Workshop; EMAC Workshop on Open-Access Exoplanet Modeling & Analysis Tools; 2023

NASA

In many astrophysical environments, such as protoplanetary formation, the collisional evolution from submillimeter-sized porous dust aggregates to large bodies is an important and complex process. We developed a Monte Carlo code that simulates the collisional evolution of a population of dust aggregates. This population has an initial distribution of velocities, aggregate sizes and porosities. Collisional partners are chosen according to aggregate cross-section and relative velocity and the collision outcome depends on their mass ratio, porosity and impact velocity, according to different regimes obtained from our previous granular-scale simulations, including adhesive and friction forces. A number of binary collisions conforms a collision chain, which corresponds to a particular stage of the granular evolution. Longer chains would correspond to denser spatial distributions of grains, or longer evolution times, for a given aggregate velocity distribution. The number of simulated chains depends on the desired statistical error. We typically averaged up to hundreds of thousands of independent collision chains to obtain size, mass and porosity distributions of aggregates, for a certain chain length. This code can also provide correlation between quantities, such as mass-porosity and size-porosity correlations. For the cases explored here, we observe significant generation of monomers and small clusters, together with growth of a few very large clusters. Collisions lead to significant compaction of the initial dust population, as expected.