Description
Directional reversals are a mechanism where bacteria undergo a drastic change in their moving directions by switching to the opposite way. Such behavior is seen in microorganisms like Myxococcus xanthus, and is essential for them to swarm and aggregate. In this study, we investigate the role of directional reversals in bacterial pattern formation. We propose and analyze a minimal model consisting of self-propelled particles moving in a two-dimensional plane, subject to angular noise and reversing at frequencies modulated by local alignment. When alignment is low, particles tend to reverse more frequently to reduce collisions, whereas highly aligned particles tend to persist their motions. Numerical simulations show that although the system does not exhibit global order, local polar order and giant number fluctuations can emerge. Our results demonstrate that directional reversals alone can generate complex spatial patterns from simple interaction rules.
