Local gravitational redshifts can bias cosmological measurements

摘要: Measurements of cosmological parameters via the distance-redshift relation usually rely on models that assume a homogenous universe. It is commonly presumed large-scale structure evident in our Universe has negligible impact measurement if distances probed observations are sufficiently large (compared to scale inhomogeneities) and averaged over different directions sky. This presumption does not hold when considering effect gravitational redshift caused by local potential, which alters light coming from all same way. Despite its small magnitude, this gives rise noticeable effects inference using SN Ia data. Assuming conservative prior knowledge potential given sampling range potentials at locations Milky-Way-like galaxies identified simulations, we show ignoring standard data analysis leads an additional systematic error ~1 per cent determination density dark energy equation state. We conclude field affects level important future aiming achieve percent-level accuracy.