Benoît Mahault
Max Planck Institute for Dynamics and Self-Organization (Göttingen), Department of Living Matter Physics

Emergent organization and pattern formation induced by motility regulation

The regulation of motility in response to environmental cues provides a platform for controlling self-propelled agents through activity landscapes, as well as a means for active systems interacting via quorum-sensing rules to regulate their aggregation dynamics. In this talk, I will present recent works dealing with emergent dynamics induced by motility regulation.
The motility response of microorganisms often involves a complex gene regulatory network, so that it occurs on a characteristic timescale that is not necessarily fast in comparison to other timescales of the dynamics. In the first part of the talk, I will present a minimal model of self-propelled motion that explicitly includes the dynamics of motility regulation, and illustrate how the presence of this additional timescale qualitatively affects the behaviour of self-propelled particles in activity landscapes.
In a second part, I will discuss the collective behaviour of multi-species active particles regulating their motility via quorum-sensing rules. I will in particular show how we identified a mechanism for dynamical pattern formation driven solely by the combined effects of motility and nonreciprocity in the inter-species couplings. Characterizing the phase of chaotic chasing bands emerging this way, we further find that it may be involved in phase-separated configuration, where it leads to anomalously slow coarsening.

B. Mahault, P. Godara and R. Golestanian, Phys. Rev. Res. 5, L022012 (2023).
Y. Duan, J. Agudo-Canalejo, R. Golestanian and B. Mahault, Phys. Rev. Lett. 131 148301 (2023).