This paper deals with a subcritical Keller-Segel equation. Starting from the stochastic particle system associated with it, we show well-posedness results and the propagation of chaos property. More precisely, we show that the empirical measure of the system tends towards the unique solution of the limit equation as the number of particles goes to infinity.Résumé. Cet article traite de l'équation de Keller-Segel dans un cadre sous-critique. À l'aide du système de particules en lien avec cette équation, nous montrons des résultats d'existence et d'unicité, puis la propagation du chaos pour ce dernier. Plus précisément, nous montrons que la mesure empirique du système tend vers l'unique solution de l'équation limite lorsque le nombre de particules tend vers l'infini.
MSC: 65C35where f : R + ×R 2 → R and χ > 0. The force field kernel K : R 2 → R 2 comes from an attractive potential : R 2 → R and is defined by, α ∈ (0, 1).(1.2)The standard Keller-Segel equation correspond to the critical case K(x) = x/|x| 2 (i.e., more singular at x = 0) and it describes a model of chemotaxis, i.e., the movement of cells (usually bacteria or amoebae) which are attracted 966 D. Godinho and C. Quiñinao by some chemical substance that they produce. This equation has been first introduced by Keller and Segel in [15,16]. Blanchet, Dolbeault and Perthame showed in [4] some nice results on existence of global weak solutions if the nonnegative parameter χ (which is the sensitivity of the bacteria to the chemo-attractant) is smaller than 8π/M where M is the initial mass (here M will always be 1 since we will deal with probability measures). For more details on the subject, see [12,13].