2DARK天文志

Abstract: We show that the observed inhomogeneities in the universe have a quintessential effect on the observable distance-redshift relations. The effect is modeled quantitatively by an extended Dyer-Roeder method that allows for two crucial physical properties of the universe: inhomogeneities in the expansion rate and the growth of nonlinear structures. On large scales, the universe is homogeneous, but due to the initially smooth matter forming opaque clumps with time, the regions the detectable light traverses get emptier and emptier compared to the average. As space expands the faster the lower the local matter density, the expansion can then accelerate along our line of sight. This phenomenon provides both a natural physical interpretation and a quantitative match for the observations from the cosmic microwave background anisotropy, the position of the baryon oscillation peak, the magnitude-redshift relations of type Ia supernovae, the local Hubble flow and the nucleosynthesis, resulting in a concordant model with 90% dark matter, 10% baryons, no dark energy and 14.8 Gyr as the age of the universe. The model is based only on the observed inhomogeneities so, unlike a large local void, it respects the cosmological principle, further explaining the late onset of the perceived acceleration as a consequence of the forming nonlinear structures. Altogether, the results seem to imply that dark energy is a mirage.