Noise Driven Avalanche Behavior in Subexcitable Media

The interaction of noise with a subexcitable chemical system gives rise to spatiotemporal behavior with novel statistical properties. Wave behavior in a photosensitive Belousov-Zhabotinsky reaction with imposed noise is monitored and statistically analyzed. Waves are initiated at sites where the accumulation of subthreshold perturbations induces local excitations, and waves propagate through the medium by a facilitated percolation process. Statistical analysis of the coherent spatiotemporal structures reveals power-law relations that indicate the system has no intrinsic length or time scale.