A HYDRODYNAMIC LIMIT FOR CHEMOTAXIS IN A GIVEN HETEROGENEOUS ENVIRONMENT IN HONOR OF WILLI JÄGER, ON THE OCCASION OF HIS 75TH BIRTHDAY.

Abstract. In this paper the first equation within a class of well known chemo-taxis systems is derived as a hydrodynamic limit from a stochastic interacting many particle system on the lattice. The cells are assumed to interact with attractive chemical molecules on a finite number of lattice sites, but they only directly interact among themselves on the same lattice site. The chemical envi-ronment is assumed to be stationary with a slowly varying mean, which results in a non-trivial macroscopic chemotaxis equation for the cells. Methodologi-cally the limiting procedure and its proofs are based on results by Koukkus [18] and Kipnis/Landim [17]. Numerical simulations extend and illustrate the theoretical findings. Content