A cosmic speed-trap: a gravity-independent test of cosmic acceleration using baryon acoustic oscillations

摘要

We propose a new and highly model-independent test of cosmic acceleration bycomparing observations of the baryon acoustic oscillation (BAO) scale at lowand intermediate redshifts: we derive a new inequality relating BAO observablesat two distinct redshifts, which must be satisfied for any reasonablehomogeneous non-accelerating model, but is violated by models similar toLambdaCDM, due to acceleration in the recent past. This test is fullyindependent of the theory of gravity (GR or otherwise), the Friedmannequations, CMB and supernova observations: the test assumes only theCosmological Principle, and that the length-scale of the BAO feature is fixedin comoving coordinates. Given realistic medium-term observations from BOSS,this test is expected to exclude all homogeneous non-accelerating models at ~4\sigma significance, and can reach ~ 7\sigma with next-generation surveys.