Constraints on supernovae dimming from photon-pseudoscalar coupling

An alternative mechanism that dims high redshift supernovae without cosmic acceleration utilizes an oscillation of photons into a pseudoscalar particle during transit. Since angular diameter distance measures are immune to the loss of photons, this ambiguity in interpretation can be resolved by combining CMB acoustic peak measurements with the recent baryon oscillation detection in galaxy power spectra. This combination excludes a nonaccelerating dark energy species at the 4σ level regardless of the level of the pseudoscalar coupling. While solutions still exist with substantial noncosmological dimming of supernovae, they may be tested with future improvement in baryon oscillation experiments.