Chemotaxis in high dimensional bacterial mixtures

Active matter systems, composed of self-propelled agents that continuously consume energy, exhibit rich non-equilibrium behavior and complex spatial organization. A key challenge is understanding how local interactions that regulate motility give rise to emergent structures, particularly in multi-species systems where ecological diversity plays a role. In this work, we investigate the role of chemotaxis—a form of motility control based on chemical gradients—in driving self-organization in dry scalar active matter. Focusing on systems with fixed population size, we show that weak, random chemotactic couplings between species can generate spatial patterns even in the absence of systematic interactions. Using a combination of theoretical analysis and numerical simulations, we first study the dynamics of a single-species system, then extend our approach to active mixtures. Our results highlight a novel mechanism for pattern formation in active matter and offer insights relevant to biological and ecological systems.