Speaker
Description
Baryon acoustic oscillation (BAO) measurements are a cornerstone of late-time cosmology, but their interpretation typically relies on assumptions about the sound horizon and a background model. We show that anisotropic BAO data alone already enable a direct, calibration-free test of the underlying geometry.
We derive an exact null relation for flat FLRW spacetime written entirely in terms of the observed shift parameters $\alpha_\perp (z)$ and $\alpha_\parallel(z)$, in which the dependence on the sound horizon cancels identically. This provides a model-independent consistency test of the distance–redshift relation. Applying the test to anisotropic BAO measurements from the Dark Energy Spectroscopic Instrument DR2 dataset, we find no evidence for deviations from flat FLRW within current uncertainties.
We also present a calibration-free reconstruction of the deceleration parameter q(z) from the radial BAO sector, showing that anisotropic BAO data already contain direct kinematic information prior to any global fit. These results highlight the potential of BAO as internal consistency tests of the cosmological framework.
| Other topic / keywords: | Model-independent cosmology; FLRW consistency tests; anisotropic BAO; calibration-free methods; geometric probes of the expansion history |
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