Nonlinear Relativistic Effects on Cosmological Redshift Drift
Abstract
Using a fully gauge-invariant approach, we compute for the first time in the literature relativistic effects on the redshift drift up to second order in cosmological perturbation theory. This is achieved by employing a set of light-cone coordinates that simplify the description of light propagation in an inhomogeneous and anisotropic universe. We show that redshift-space distortion occurs only as a second-order effect whereas, as known, it is not present among the linear perturbations. We then derive analytical expressions of the bispectrum for the leading-order perturbative contributions on sub-Hubble scales, providing some numerical evaluations. Our finding is that, at low redshift and for large momenta, the non-linearities in the bispectrum are enhanced more than the squared power spectrum.
Cite
@article{arxiv.2604.26690,
title = {Nonlinear Relativistic Effects on Cosmological Redshift Drift},
author = {Pierre Béchaz and Giuseppe Fanizza and Giovanni Marozzi and Matheus R. Medeiros Silva},
journal= {arXiv preprint arXiv:2604.26690},
year = {2026}
}
Comments
49 pages, 5 figures