Analysis of Gaia Data Release 3 Parallax bias in the Galactic plane

TL;DR

This study evaluates the Gaia DR3 parallax bias correction in the Galactic plane, finds the existing correction sample-dependent and ineffective there, and proposes a new correction tailored for the Galactic plane to improve accuracy.

Contribution

The paper demonstrates the limitations of the Lindegren et al. (L21) correction in the Galactic plane and introduces a new, more accurate correction method for this region.

Findings

L21 correction is sample-dependent and less effective in the Galactic plane.

A new correction method improves parallax bias estimates in the Galactic plane.

Differences between corrections can reach up to 0.01 mas for certain sources.

Abstract

The systematic errors are inevitable in Gaia published astrometric data. Lindegren et al. (L21) proposed a global recipe to correct for the GEDR3 parallax zero point offset, which did not consider the Galactic plane. The applicability of their correction model to the Galactic plane remains uncertain. We attempt to have an independent investigation into the sample dependence of the L21 correction, and its applicability to the Galactic plane. We collect various samples, including quasars, binaries, and sources with parallaxes from other surveys or methods, to validate the L21 correction, especially in the Galactic plane. We conclude that the L21 correction exhibits sample dependence, and does not apply effectively to the Galactic plane. We present a new parallax bias correction applying to the Galactic plane, offering improvements over the existing L21 correction. The correction difference between L21 and this work can go up to 0.01 mas within certain ranges of magnitude and colour. This work provides an additional recipe for users of Gaia parallaxes, especially for sources located near the Galactic plane.