We discuss how the baryon acoustic oscillation ( BAO ) signatures in the galaxy power spectrum can distinguish between modified gravity and the cosmological constant as the source of cosmic acceleration .
To this end we consider a model characterized by a parameter n , which corresponds to the Dvali-Gabadadze-Porrati ( DGP ) model if n = 2 and reduces to the standard spatially flat cosmological constant concordance model for n equal to infinity .
We find that the different expansion histories of the modified gravity models systematically shifts the peak positions of BAO .
A preliminary analysis using the current SDSS LRG sample indicates that the original DGP model is disfavored unless the matter density parameter exceeds 0.3 .
The constraints will be strongly tightened with future spectroscopic samples of galaxies at high redshifts .
We demonstrate that WFMOS , in collaboration with other surveys such as Planck , will powerfully constrain modified gravity alternatives to dark energy as the explanation of cosmic acceleration .