Coarsening of topological defects in 2D polar active matter

We numerically study the coarsening of topological defects in 2D polar active matter and make several interesting observations and predictions. (i) The long time state is characterized by nonzero density of defects, in stark contrast to theoretical expectations. (ii) The kinetics of defect coarsening shows power law decay to steady state, as opposed to exponential decay in thermal equilibrium. (iii) Observations (i) and (ii) together suggest emergent screening of topological charges due to activity. (iv) Nontrivial defect coarsening in the active model leads to nontrivial steady state patterns. We investigate, characterize, and validate these patterns and discuss their biological significance.