Axial Bianchi I meets drifting extragalactic sources

TL;DR

This paper recalculates the drift of extragalactic sources in axial Bianchi I universes, resolving previous discrepancies and improving the accuracy of models relevant for Gaia data analysis and cosmology.

Contribution

It provides a corrected ab initio computation of source drift in axial Bianchi I universes, settling a long-standing disagreement in the field.

Findings

Resolved previous computational disagreement in source drift calculations.

Confirmed the accuracy of Marcori et al.'s approach.

Implications for Gaia data analysis and cosmological parameter estimation.

Abstract

We recompute {\it ab initio} the drift of comoving sources in axial Bianchi I universes. Our result resolves the long-standing disagreement between the computations by Quercellini et al. from 2009 and by Marcori et al. from 2018 in favour of the latter. These computations have a potential impact on Gaia data analysis and cosmological parameter estimation.