Smoothing effect and uniqueness for aggregation diffusion models

Abstract

We consider aggregation-diffusion models for a density of mass in ${\mathbb{R}}^d$, $d\ge 2$, where the diffusion can be either linear or of porous medium type, while the aggregation effect is governed by the attractive Newtonian or Bessel potential. It is well known that the dynamics can be interpreted as Wasserstein gradient flow of the natural free energy of the system, and that, under suitable assumptions on the diffusion exponent and the mass of the initial datum, solutions exist globally in time. In these regimes, we perform the analysis of the discrete variational approach by means of the JKO scheme. We establish a sharp $L^{\infty }$ smoothing effect, which proves to be of same rate as that of the porous medium equation. Thanks to this estimate, we obtain uniqueness of global gradient flow solutions for initial data of finite energy and, in the diffusion dominated regime, for measure data having finite second moment. We prove the energy dissipation equality and characterize the gradient flow in terms of suitable evolution variational inequalities. In the fair competition regime, we show uniform extinction of solutions for large time under smallness conditions on the mass.