Hypocycloidal resonance attractor for rigidly rotating spiral waves

Rigidly rotating spiral waves are investigated in the light sensitive excitable Belousov–Zhabotinsky reaction under local feedback control. Each light pulse is applied at a moment that corresponds to the passage of the wave front through a particular measuring point. For a small distance between the measuring point and the initial location of the spiral core, a resonance attractor with hypocycloidal shape is observed, whereas for a larger distance an epicycloidal resonance attractor occurs. The size of the attractor can be changed by introducing a time delay. Experimental and numerical results are compared with an earlier developed theory on the resonance attractor.