Special Session 43: Hamiltonian Dynamics and Celestial Mechanics

Exploration of billiards with Keplerian potential
Anna Maria Cherubini
University of Salento
Italy
Co-Author(s):    Vivina L. Barutello and Irene De Blasi
Abstract:
We study a class of elliptic billiards with a Keplerian potential inside, considering two cases: a reflective one, where the particle reflects elastically on the boundary, and a refractive one where the particle can cross the billiard`s boundary entering a region with a harmonic potential. In the latter case, the dynamics is given by concatenations of inner and outer arcs, connected by a refraction law. In recent papers these billiards have been extensively studied in order to identify which conditions give rise to either regular or chaotic dynamics. We complete the study by analysing the non focused reflective case. We then analyse the focused and non focused refractive case, where no results on integrability are known except from the centred circular case, by providing an extensive numerical analysis. We present also a theoretical result regarding the linear stability of homotetic equilibrium orbits in the reflective case for general ellipses, highlighting the possible presence of bifurcations even in the integrable case.