Sharp Sobolev estimates for concentration of solutions to an aggregation-diffusion equation

Abstract

We consider the drift-diffusion equation $u_t-\epsilon\Delta u + \nabla \cdot(u\nabla K^*u)=0$ in the whole space with global-in-time solutions bounded in all Sobolev spaces; for simplicity, we restrict ourselves to the model case $K(x)=-|x|$. We quantify the mass concentration phenomenon, a genuinely nonlinear effect, for radially symmetric solutions of this equation for small diffusivity $\epsilon$ studied in our previous paper [3], obtaining optimal sharp upper and lower bounds for Sobolev norms.