Scaling Behavior of a Critical Jamming System Under Active Forces and Thermal Fluctuations

Jamming in particulate matter is a common phenomenon which has been argued to be relevant to synthetic and biological systems alike. In recent years, much advancement in the understanding of athermal critical Jamming has been taken place. However, our current understanding of active jamming is crucially lacking. While it is natural to expect that applying high enough self-propulsion forces to initially passive jammed systems will result into unjamming of the systems, what kind of universal behavior (if any) is observed around the athermal critical jamming point when active or thermal fluctuations are added remains unknown. By means of direct numerical simulations, we probe the effect of 1) persistent active and 2) thermal fluctuations on a dense, athermal jammed system of spheres in 2D and ask the question of whether a strictly jammed system (understood as remaining above isostaticity) exists at non-zero fluctuations strengths. We define both the critical strength of active forces and thermal fluctuations based on the evolution of particles' contact numbers. We observe that both types of perturbations lead to identical scaling behavior with pressure, i.e. with distance from the athermal jamming point.