Structural Instability in the Golden-Mean Semi-Siegel Hénon Family
Consider a dissipative quadratic Hénon map Hμ,ν that has a fixed point in C2 with multipliers μ and ν. As ν goes to 0, the dynamics of Hμ,ν degenerates to that of the quadratic polynomial fμ that has a fixed point in C with multiplier μ. Due to work of Hubbard and Oberste-Vorth, and Radu and Tanase respectively, the structure of the Julia set J+ of Hμ,ν was shown to be stable in the hyperbolic (|μ|<1) and the semi-parabolic case (μ is a rational rotation). Using a renormalization approach inspired by the work of Lyubich and Martens for Feigenbaum Hénon maps, we show that structural stability fails in the golden-mean semi-Siegel case (μ is the golden-mean rotation). This is joint work with M. Yampolsky.