Periodic KPP equations in hyperbolic space

Abstract

We study Fisher-KPP equations on hyperbolic space with reactions periodic in a Busemann coordinate or in the distance from a point or a geodesic. We determine spectral thresholds for extinction and persistence, including critical extinction from $L^2$ data, and characterize the signed speeds of horospherical fronts. In the hyperbolic plane, we construct a smooth periodic reaction admitting a positive stationary solution that decays away from a geodesic, and determine the spreading speed along the geodesic. For constant linear growth, we obtain logarithmic level positions with bounded error for balls, horoballs and geodesic tubes.