Redshift drift cosmography for model-independent cosmological inference

TL;DR

This paper introduces a model-independent cosmographic approach to analyze redshift drift signals, accounting for anisotropies and inhomogeneities, enabling more flexible cosmological inferences from nearby sources.

Contribution

It develops a new cosmographic framework for analyzing redshift drift signals without assuming a specific metric, incorporating effects of anisotropies and inhomogeneities.

Findings

Redshift drift signals can be expressed in terms of an effective deceleration parameter.

The framework links source position drift to redshift drift in a nontrivial way.

The lowest-order redshift drift signal is described by a finite set of interpretable coefficients.

Abstract

We develop a cosmographic framework for analysing 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.