Non-linear evolution of the BAO scale in alternative theories of gravity
The scale of Baryon Acoustic Oscillations (BAO) imprinted in the matter distribution is known to suffer sub-percent deviations from being a perfect standard ruler due to non-linear corrections. I will give an overview of historical and recent developments in alternative theories of gravity and present a computation of the BAO shift based on perturbation theory (à la Bellini-Sawicki) and a peak-background split (à la Sherwin-Zaldarriaga), valid for a large class of models. The BAO shift is modified by the enhanced growth of linear perturbations, as well as by novel, non-linear gravitational effects. The prediction can be larger than the standard value by 45-82% at z=0 for simple alternatives to a cosmological constant, and in some cases presents a characteristic time evolution. Although small, this effect might be within the reach of future galaxy surveys, and might have implications for BAO reconstruction in theories other than Einstein's.