Redshift drift cosmography for model-independent cosmological inference
Asta Heinesen
Abstract
We develop a cosmographic framework for analyzing redshift drift signals of nearby sources model independently, i.e., without making assumptions about the metric description of the Universe. We show that the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) prediction is altered nontrivially by regional anisotropies and inhomogeneities. In particular, we find that the position drift of the sources is nontrivially linked to the redshift drift signal. The redshift drift signal for nearby sources might be formulated in terms of an effective deceleration parameter, which reduces to the FLRW deceleration parameter in the homogeneous and isotropic limit. The presented cosmographic framework can be used for model-independent data analysis, exploiting the fact that the exact anisotropic redshift drift signal at lowest order in redshift is given by a finite set of physically interpretable coefficients. We discuss physical limits of interest as well as challenges related to the framework.