The Pristine Survey -- XXVII. Journey to the Galactic outskirts -- Mapping the outer halo red giant stars down to the very metal-poor end

Abstract

Context: In the context of Galactic archaeology, the outer halo remains relatively unexplored with respect to its metallicity distribution, merger debris, and the abundance of known very/extremely metal-poor ([Fe/H]<-2.5) stars. Aim: We utilize the Pristine survey's publicly available, Pristine data release 1 (PDR1) and Pristine-Gaia synthetic (PGS) catalogues of photometric metallicities, to select Red Giant Branch (RGB) stars in the outer halo. Methods: The RGB selection pipeline selects giants based on the absence of a well-measured parallax in the brightness range where dwarfs have reasonable parallax estimate from Gaia DR3 data. The photometric distances are calculated using a BaSTI-isochrone fitting code and the photometric metallicities. Results: Photometric distances derived from PDR1- and PGS-giants show typical uncertainties of 12% and a scatter of up to 20% and 40% respectively, when validated against inverted-parallax and Starhorse-code distances. The PDR1-giants catalogue provides a low-to-no bias view of the metallicity structure versus distance compared to the PGS-giants catalogue (with a distance-metallicity selection bias), while the PGS-giants catalogue provides an all-sky view of the outer halo, especially in the VMP end. The PDR1-giants catalogue is used to study the metallicity distribution function of the halo out to ~100 kpc, using Gaussian Mixture Model decomposition. Additionally, we use the PDR1-giants with radial velocities from spectroscopic surveys to map the metallicity view of the integrals-of-motion space where accreted dwarf galaxy debris conserve their orbital parameters for a long time. Using the PGS-giants catalogue, we associate 41 stars tentatively to the stellar counterpart of the Magellanic stream in the VMP end, out to 70 kpc. Conclusions: We publish two RGB catalogues between -4.0<[Fe/H]<+0.1 with reliable photometric distances and metallicities.

Submitted to A&A, 25 pages (19 Figures) + 4 pages (6 Figures) in Appendix. Comments are very welcome, enjoy reading! The catalogues will be published upon acceptance

References in corpus (76)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The mass distribution and gravitational potential of the Milky Way
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• The Radial Velocity Experiment (RAVE): first data release
• Gaia Early Data Release 3: Photometric content and validation
• Two Stellar Components in the Halo of the Milky Way
• The GALAH+ Survey: Third Data Release
• The Milky Way Tomography with SDSS: II. Stellar Metallicity
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• Tango for three: Sagittarius, LMC, and the Milky Way
• Is the SMC Bound to the LMC? The HST Proper Motion of the SMC
• The Origin of the Magellanic Stream and Its Leading Arm
• Gaia Data Release 3: Processing and validation of BP/RP low-resolution spectral data
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• The Hercules-Aquila Cloud
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Overview of the DESI Milky Way Survey
• The chemical characterisation of halo substructure in the Milky Way based on APOGEE
• Robust Data-driven Metallicities for 175 Million Stars from Gaia XP Spectra
• Quantifying the impact of the Large Magellanic Cloud on the structure of the Milky Way's dark matter halo using Basis Function Expansions
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• The Poor Old Heart of the Milky Way
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• Timing the Early Assembly of the Milky Way with the H3 Survey
• StarHorse results for spectroscopic surveys + Gaia DR3: Chrono-chemical populations in the solar vicinity, the genuine thick disk, and young-alpha rich stars
• The Pristine survey X: a large population of low-metallicity stars permeates the Galactic disk
• The oldest and most metal poor stars in the APOSTLE Local Group simulations
• The Gaia DR3 view of dynamical substructure in the stellar halo near the Sun
• GASTRO library I: the simulated chemodynamical properties of several GSE-like stellar halos
• The $>100$ kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars
• The Pristine survey VIII: The metallicity distribution function of the Milky Way halo down to the extremely metal-poor regime
• Nitrogen enrichment and clustered star formation at the dawn of the Galaxy
• The Geometry of Sagittarius Stream from Pan-STARRS1 3$\pi$ RR Lyrae
• Evidence of a dwarf galaxy stream populating the inner Milky Way Halo
• The Progenitors of the Milky Way Stellar Halo: Big Bricks Favoured over Little Bricks
• The Pisces Plume and the Magellanic Wake
• The Pristine survey III: Spectroscopic confirmation of an efficient search for extremely metal-poor stars
• Pristine IX: CFHT ESPaDOnS Spectroscopic Analysis of 115 Bright Metal-Poor Candidate Stars
• Beyond spectroscopy. I. Metallicities, distances, and age estimates for over twenty million stars from SMSS DR2 and Gaia EDR3
• Stellar halo substructure generated by bar resonances
• The Pristine survey -- XXIII. Data Release 1 and an all-sky metallicity catalogue based on Gaia DR3 BP/RP spectro-photometry
• Substructure in the stellar halo near the Sun. I. Data-driven clustering in Integrals of Motion space
• Substructure in the stellar halo near the Sun. II. Characterisation of independent structures
• The Pristine survey -- XII: Gemini-GRACES chemo-dynamical study of newly discovered extremely metal-poor stars in the Galaxy
• The Outer Halo of the Milky Way as Probed by RR Lyr Variables from the Palomar Transient Facility
• Discovery of the Magellanic Stellar Stream Out to 100 Kiloparsecs
• Radial halo substructure in harmony with the Galactic bar
• Probing the Galactic Halo with RR Lyrae Stars. II. The Substructures of the Milky Way
• Distant Echoes of the Milky Way's Last Major Merger
• DESI Early Data Release Milky Way Survey Value-Added Catalogue
• To the Galactic Virial Radius with Hyper Suprime-Cam
• The Pristine survey -- VII. A cleaner view of the Galactic outer halo using blue horizontal branch stars
• The stellar halo in Local Group Hestia simulations I. The in-situ component and the effect of mergers
• The Unmixed Debris of Gaia-Sausage/Enceladus in the Form of a Pair of Halo Stellar Overdensities
• The Cetus-Palca stream: A disrupted small dwarf galaxy. A prequel to the science possible with WEAVE with precise spectro-photometric distances
• Probing the Galactic halo with RR Lyrae stars $-$ III. The chemical and kinematic properties of the stellar halo
• The Pristine survey -- XV. A CFHT ESPaDOnS view on the Milky Way halo and disc populations
• The Pristine survey -- XVII. The C-19 stream is dynamically hot and more extended than previously thought
• The Pristine survey II: a sample of bright stars observed with FEROS
• The Pristine survey XIV: chemical analysis of two ultra-metal-poor stars
• Discovery of Magellanic Stellar Debris in the H3 Survey
• What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants
• Gaia's brightest very metal-poor (VMP) stars. Metallicity catalogue of a thousand VMP stars from Gaia's radial velocity spectrometer spectra
• Chemodynamical Analysis of Metal-rich High-eccentricity Stars in the Milky Way's Disk
• The Pristine Inner Galaxy Survey (PIGS) X. Probing the early chemical evolution of the Sagittarius dwarf galaxy with carbon abundances
• Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function
• The Pristine survey: XXV. The very metal-poor Galaxy: Chemodynamics through the follow-up of the Pristine-Gaia synthetic catalogue
• Hidden deep in the halo: selection of a reduced proper motion halo catalogue and mining retrograde streams in the velocity space
• Deciphering the Kinematic Substructure of Local Dark Matter with LAMOST K Giants

Cited by in corpus (1)

• An ancient system hidden in the Galactic plane?