Special Session 42: Hamiltonian Dynamics and Celestial Mechanics

On the Birkhoff conjecture for Kepler billiards
Vivina Barutello
University of Turin
Italy
Co-Author(s):    
Abstract:
We investigate the integrability of Kepler billiards-mechanical billiard systems in which a particle moves under the influence of a Keplerian potential and reflects elastically at the boundary of a strictly convex planar domain. Our main result establishes that, except possibly for one location of the gravitational center, analytic integrability at high energies occurs only when the domain is an ellipse and the center is placed at one of its foci. This provides a partial affirmative answer to a Keplerian analogue of the classical Birkhoff-Poritsky Conjecture. Our approach is based on the construction of symbolic dynamics arising from chaotic subsys- tems that emerge in the high-energy regime.