The Pristine survey: XXV. The very metal-poor Galaxy: Chemodynamics through the follow-up of the Pristine-Gaia synthetic catalogue

Abstract

The Pristine-\textit{Gaia} synthetic catalogue provides reliable photometric metallicities for $\sim$30 million FGK stars using the Pristine survey model and Gaia XP spectra. We perform the first low-to-medium-resolution spectroscopic follow-up of bright (G<15) and distant (up to 35 kpc) very and extremely metal-poor (V/EMP, [Fe/H]<-2.5) red giant branch stars from this. We use Isaac Newton Telescope/Intermediate Dispersion Spectrograph (INT/IDS) observations centred around the calcium triplet region ideal for V/EMP stars. We find that 76\% of our stars indeed have [Fe/H]<-2.5 with these inferred spectroscopic metallicities and only 3\% are outliers with [Fe/H] > -2.0. We report a success rate of 77\% and 38\% in finding stars with [Fe/H]<-2.5 and -3.0 respectively. This will allow for 10,000-20,000 homogeneously analysed EMP stars using the WEAVE survey follow-up of Pristine EMP candidates. We associate 20\%, 46\%, and 34\% of the stars to be confined to the disc plane, or to have inner and outer halo orbits, respectively. We also associate these V/EMP stars to known accretion events such as Gaia-Enceladus-Sausage (GES), LMS-1/Wukong, Thamnos, Helmi streams, Sagittarius, Sequoia, etc. For the stars that orbit close to the disc plane, we find that the prograde region with low vertical action is overdense with a significance of 4$\sigma$ as compared to its retrograde counterpart. We also find three new (brightest) members of the most metal-poor stellar stream, C-19, one of which is 50${}^{\circ }$ away from the main body of the stream. Our measured mean metallicity, velocity dispersion, and stream width are consistent with the literature, but our results favour a higher distance ($\sim$21.5 kpc) for the stream. We publish a catalogue (and 1D spectra) of 215 V/EMP stars from this spectroscopic follow-up and showcase the power of chemokinematic analysis of V/EMP end.

arXiv commentPublished version. The catalogue of 215 V/EMP stars and their reduced 1D spectra is available here https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/695/A112

References in corpus (109)

• The NumPy array: a structure for efficient numerical computation
• The Sloan Digital Sky Survey: Technical Summary
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 3: Summary of the content and survey properties
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Local Kinematics and the Local Standard of Rest
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The mass distribution and gravitational potential of the Milky Way
• Co-formation of the Galactic disc and the stellar halo
• 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
• The GALAH+ Survey: Third Data Release
• Simulations of Galaxy Formation in a Lambda CDM Universe II: The Fine Structure of Simulated Galactic Disks
• AGAMA: Action-based galaxy modelling architecture
• Near-Field Cosmology with Metal-Poor Stars
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Gaia EDR3 view on Galactic globular clusters
• Building up the Stellar Halo of the Galaxy
• The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
• SkyMapper Southern Survey: First Data Release (DR1)
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The Structure of the Milky Way's Bar Outside the Bulge
• In disguise or out of reach: first clues about in-situ and accreted stars in the stellar halo of the Milky Way from Gaia DR2
• The photometric structure of the inner Galaxy
• The Biggest Splash
• The Pristine survey I: Mining the Galaxy for the most metal-poor stars
• Gaia Data Release 3: Analysis of RVS spectra using the General Stellar Parametriser from spectroscopy
• J-PLUS: The Javalambre Photometric Local Universe Survey
• Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G=18.5
• StarHorse: A Bayesian tool for determining stellar masses, ages, distances, and extinctions for field stars
• Mapping the substructure in the Galactic halo with the next generation of astrometric satellites
• The Milky Way has no in-situ halo other than the heated thick disc. Composition of the stellar halo and age-dating the last significant merger with Gaia DR2 and APOGEE
• 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
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• Chemical Evolution in Hierarchical Models of Cosmic Structure II: The Formation of the Milky Way Stellar Halo and the Distribution of the Oldest Stars
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• The distribution and kinematics of early high-sigma peaks in present-day haloes: implications for rare objects and old stellar populations
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Charting the Galactic acceleration field I. A search for stellar streams with Gaia DR2 and EDR3 with follow-up from ESPaDOnS and UVES
• The $R$-Process Alliance: First Release from the Southern Search for $r$-Process-Enhanced Stars in the Galactic Halo
• Where are the most ancient stars in the Milky Way?
• The R-Process Alliance: First Release from the Northern Search for r-Process Enhanced Metal-Poor Stars in the Galactic Halo
• Dynamical Relics of the Ancient Galactic Halo
• Robust Data-driven Metallicities for 175 Million Stars from Gaia XP Spectra
• The chemical characterisation of halo substructure in the Milky Way based on APOGEE
• The Poor Old Heart of the Milky Way
• Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
• Tracing the formation of the Milky Way through ultra metal-poor stars
• Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey
• The Near Infrared Ca II Triplet as Metallicity Indicator: II Extension to extremely metal-poor metallicity regimes
• The Best and Brightest Metal-Poor Stars
• A Sequoia in the Garden: FSR 1758 - Dwarf Galaxy or Giant Globular Cluster?
• $S^5$: The Orbital and Chemical Properties of One Dozen Stellar Streams
• 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 Pristine Inner Galaxy Survey (PIGS) I: Tracing the kinematics of metal-poor stars in the Galactic bulge
• Vaex: Big Data exploration in the era of Gaia
• The Pristine Survey IV: Approaching the Galactic metallicity floor with the discovery of an ultra metal-poor star
• The Gaia DR3 view of dynamical substructure in the stellar halo near the Sun
• The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge
• The Pristine Survey -- VI. The first three years of medium-resolution follow-up spectroscopy of Pristine EMP star candidates
• 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
• Reviving old controversies: is the early Galaxy flat or round? Investigations into the early phases of the Milky Way formation through stellar kinematics and chemical abundances
• Exploring the origin of low-metallicity stars in Milky Way-like galaxies with the NIHAO-UHD simulations
• Pristine IX: CFHT ESPaDOnS Spectroscopic Analysis of 115 Bright Metal-Poor Candidate Stars
• The Pristine survey III: Spectroscopic confirmation of an efficient search for extremely metal-poor stars
• A stellar stream remnant of a globular cluster below the metallicity floor
• The tidal remnant of an unusually metal-poor globular cluster
• The Phoenix stream: a cold stream in the Southern hemisphere
• Data Release 2 of S-PLUS: accurate template-fitting based photometry covering $\sim$1000 square degrees in 12 optical filters
• Stellar halo substructure generated by bar resonances
• The Pristine survey -- XXIII. Data Release 1 and an all-sky metallicity catalogue based on Gaia DR3 BP/RP spectro-photometry
• Substructure in the stellar halo near the Sun. II. Characterisation of independent structures
• Substructure in the stellar halo near the Sun. I. Data-driven clustering in Integrals of Motion space
• Dynamically constraining the length of the Milky Way bar
• The Pristine survey -- XVI. The metallicity of 26 stellar streams around the Milky Way detected with the STREAMFINDER in Gaia EDR3
• The Pristine survey -- XII: Gemini-GRACES chemo-dynamical study of newly discovered extremely metal-poor stars in the Galaxy
• The origin of metal-poor stars on prograde disk orbits in FIRE simulations of Milky Way-mass galaxies
• High resolution spectroscopic follow-up of the most metal-poor candidates from SkyMapper DR1.1
• The Pristine Dwarf-Galaxy survey -- IV. Probing the outskirts of the dwarf galaxy Boötes I
• The COMBS survey I: Chemical Origins of Metal-Poor Stars in the Galactic Bulge
• The Pristine survey XIII: Uncovering the very metal-poor tail of the thin disc
• Discovery of the local counterpart of disc galaxies at z > 4: The oldest thin disc of the Milky Way using Gaia-RVS
• The Pristine Inner Galaxy Survey (PIGS) V: a chemo-dynamical investigation of the early assembly of the Milky Way with the most metal-poor stars in the bulge
• The 33 M${}_{\odot }$ black hole Gaia BH3 is part of the disrupted ED-2 star cluster
• The Cetus-Palca stream: A disrupted small dwarf galaxy. A prequel to the science possible with WEAVE with precise spectro-photometric distances
• The Pristine survey -- XVII. The C-19 stream is dynamically hot and more extended than previously thought
• The Pristine survey -- XV. A CFHT ESPaDOnS view on the Milky Way halo and disc populations
• Information content of BP/RP spectra in Gaia DR3
• The Pristine survey II: a sample of bright stars observed with FEROS
• The Pristine survey XIV: chemical analysis of two ultra-metal-poor stars
• The Pristine survey XVIII: C-19: Tidal debris of a dark matter-dominated globular cluster?
• Probing the early Milky Way with GHOST spectra of an extremely metal-poor star in the Galactic disk
• ED-2: a cold but not so narrow stellar stream crossing the Solar neighbourhood
• On the metal-poor edge of the Milky Way "thin disc"
• Gaia's brightest very metal-poor (VMP) stars. Metallicity catalogue of a thousand VMP stars from Gaia's radial velocity spectrometer spectra
• Could very low-metallicity stars with rotation-dominated orbits have been shepherded by the bar?
• Hidden deep in the halo: selection of a reduced proper motion halo catalogue and mining retrograde streams in the velocity space

Cited by in corpus (6)

• The Pristine survey: XXVII. The extremely metal-poor stream C-19 stretches over more than 100 degrees
• The Pristine survey XXVIII. Journey to the Galactic outskirts: Mapping the outer halo red giant stars down to the very metal-poor end
• A slow spin to win: The gradual kinematic evolution across metallicities of the proto-Galaxy to the high-$\alpha$ disc
• The metal-poor tail of the APOGEE survey I. Uncovering [Fe/H] < -2.5 stars from the inner Galaxy to the Magellanic Clouds
• A test of Ca ii H & K photometry for isolating massive globular clusters below the metallicity floor
• An ancient system hidden in the Galactic plane?