Threshold velocity for collisional growth of porous dust aggregates consisting of cohesive frictionless spheres

TL;DR

This study investigates how interparticle tangential friction influences the collisional growth of porous dust aggregates, revealing that frictionless spheres have a lower threshold velocity for growth, which impacts planet formation models.

Contribution

The paper demonstrates the significant effect of tangential friction on dust aggregate growth thresholds through systematic numerical simulations.

Findings

Frictionless dust aggregates have a lower threshold velocity for growth.

Tangential interactions significantly affect collisional outcomes.

The existing predictive equations for threshold velocity need revision.

Abstract

Understanding the collisional outcomes of dust aggregates and dependence on material properties of the constituting particles is of great importance toward understanding planet formation. Recent numerical simulations have revealed that interparticle tangential friction plays a crucial role in energy dissipation during collisions between porous dust aggregates; however, the importance of friction on the collisional growth of dust aggregates remains poorly understood. Here we demonstrate the effects of interparticle tangential friction on the collisional growth of dust aggregates. We performed numerical simulations of collisions between equal-mass porous dust aggregates consisting of cohesive and frictionless spheres. We changed the collision velocity and impact angle systematically and calculated the collisional growth efficiency as a function of the collision velocity. We found that the threshold velocity for collisional growth decreases when dust aggregates are made of frictionless spheres as compared to frictional spheres. Our results highlight the importance of tangential interactions on the collisional behavior of dust aggregates and indicate that the predictive equation for threshold velocity should be reconstructed.