Get access

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




We propose a new and highly model-independent test of cosmic acceleration by comparing observations of the baryon acoustic oscillation (BAO) scale at low and intermediate redshifts: we derive a new inequality relating BAO observables at two distinct redshifts, which must be satisfied for any reasonable homogeneous non-accelerating model, but is violated by models similar to Λ cold dark matter, due to acceleration in the recent past. This test is fully independent of the theory of gravity (general relativity or otherwise), the Friedmann equations, cosmic microwave background and supernova observations: the test assumes only the cosmological principle, and that the length-scale of the BAO feature is fixed in comoving coordinates. Given realistic medium-term observations from the Baryon Oscillation Spectroscopic Survey, this test is expected to exclude all homogeneous non-accelerating models at ∼4σ significance, and can reach inline image with next-generation surveys.