Mapping the Milky Way in Six Dimensions: A contiguous, homogenised, phase-space catalogue of Gaia DR3 tracers up to 250 kpc

arXiv:2609.28652 · astro-ph.GA · Submitted 2026-09-23 · Read on arXiv

astro-ph.GA

Submitted: 2026-09-23

Updated: 2026-09-23

Comments: 46 pages, 28 figures. Submitted to Astronomy & Astrophysics (A&A). The code and the data will be made public once the paper is accepted for publication. In the meantime, we are happy to share the data with anyone, upon personal request, who would like to use it for any research problem

License: http://creativecommons.org/licenses/by/4.0/

The gist: We present a comprehensive, homogenised catalogue of 32, 552, 876 stellar sources with full 6D phase-space information, spanning Galactocentric distances from the inner galaxy (5,kpc) to the outer

Terminology

Abstract

We present a comprehensive, homogenised catalogue of 32, 552, 876 stellar sources with full 6D phase-space information, spanning Galactocentric distances from the inner galaxy (5,kpc) to the outer halo (about!250,kpc). By cross-matching Gaia DR3 astrometry with spectrophotometric distances and line-of-sight velocities from 14 surveys (including desi, sdss-boss, apogee, lamost, galah, and ges), we achieve median fractional distance uncertainties of about2.7% for d helio 15,kpc, and about29% for 15<d helio 250,kpc. The catalogue-wide median fractional radial velocity uncertainty is about8.31%. Gaia-anchored zero-point corrections and statistical normalisation suppress both random and systematic errors. Furthermore, we derive spectrophotometric parallaxes from joint photometric and spectroscopic data. Overlapping survey data is aggregated to replace unreliable values and supplement absent velocities, improving completeness and internal consistency. This multi-survey synthesis is externally validated against globular clusters, dwarf galaxies, and stellar streams, yielding precise kinematics. Notably, the sample features 517, 123 halo stars extending well beyond the Gaia parallax limit (!10,kpc). These predominantly faint (G > 17) and metal-poor ([Fe/H] < -1) tracers, including RR Lyrae, blue horizontal-branch, and K giant stars, constitute the largest well-calibrated sample of outer-halo tracers to date. This unique dataset is ideal for multi-component mass modelling, galactic archaeology, and dark matter searches across the Milky Way.

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