Equilibria for an Aggregation Model with Two Species.

We consider an aggregation model for two interacting species. The coupling between the species is via their velocities, which incorporate self- and cross-interactions. Our main interest is categorizing the possible steady states of the considered model in two dimensions. Notably, we identify their regions of existence and stability in the parameter space. For assessing the stability we use a combination of variational tools (based on the gradient flow formulation of the model and the associated energy) and linear stability analysis (perturbing the boundaries of the species' supports). We rely on numerical investigations for those steady states that are not analytically tractable. Finally we perform a two-scale expansion to characterize the steady state in the limit of asymptotically weak cross-interactions.