Spreading properties for non-autonomous Fisher-KPP equations with nonlocal diffusion

Abstract: We investigate the asymptotic speed of spread of the solutions of a non-autonomous Fisher-KPP equation with nonlocal diffusion, driven by a thin-tailed kernel. In this paper, we are concerned with both compactly supported and exponentially decaying initial data. For general time heterogeneity, we provide lower and upper estimates of the spreading speed of the solutions, which is expressed in term of the least mean of the time varying coefficients of the problem. Under some stronger time averaging assumptions for these coefficients, we prove that these solutions propagate with some determined speed. In this analysis, an important difficulty comes from the lake of regularization for the solutions arising with nonlocal diffusion. Through delicate analysis we derive some regularity estimates (of uniform continuity type for the large time) for some solutions of the logistic equation equipped with suitable initial data. These results are then used to handle more general nonlinearities and derive a rather general spreading speed results.