Model independent tests of the standard cosmological model

The dark energy problem has led to speculation that not only may ΛCDM be wrong, but that the Friedmann-Lemaître-Robertson-Walker models themselves may not even provide the correct family of background models. We discuss how direct measurements of H(z) can be used to formulate tests of the standard paradigm in cosmology. On their own, such measurements can be used to test for deviations from flat ΛCDM. When combined with supernovae distances, Hubble rate measurements provide a test of the Copernican principle and the homogeneity assumption of the standard model, which is independent of dark energy or a metric based the theory of gravity. A modification of this test also provides a model independent observable for flatness which decorrelates curvature determination from dark energy. We investigate these tests using Hubble rate measurements from age data, as well as from a Hubble rate inferred from recent measurements of the baryon acoustic oscillations. While the current data are too weak to say anything significant, these tests are exciting prospects for the future. © 2010 The American Physical Society.