The chemical characterisation of halo substructure in the Milky Way based on APOGEE

Abstract

Galactic haloes in a $\Lambda$-CDM universe are predicted to host today a swarm of debris resulting from cannibalised dwarf galaxies. The chemo-dynamical information recorded in their stellar populations helps elucidate their nature, constraining the assembly history of the Galaxy. Using data from APOGEE and \textit{Gaia}, we examine the chemical properties of various halo substructures, considering elements that sample various nucleosynthetic pathways. The systems studied are Heracles, \textit{Gaia}-Enceladus/Sausage (GES), the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1, Arjuna, I'itoi, Nyx, Icarus, and Pontus. Abundance patterns of all substructures are cross-compared in a statistically robust fashion. Our main findings include: {\it i)} the chemical properties of most substructures studied match qualitatively those of dwarf Milky Way satellites, such as the Sagittarius dSph. Exceptions are Nyx and Aleph, which are chemically similar to disc stars, implying that these substructures were likely formed \textit{in situ}; {\it ii)} Heracles differs chemically from {\it in situ} populations such as Aurora and its inner halo counterparts in a statistically significant way. The differences suggest that the star formation rate was lower in Heracles than in the early Milky Way; {\it iii)} the chemistry of Arjuna, LMS-1, and I'itoi is indistinguishable from that of GES, suggesting a possible common origin; {\it iv)} all three Sequoia samples studied are qualitatively similar. However, only two of those samples present chemistry that is consistent with GES in a statistically significant fashion; {\it v)} the abundance patterns of the Helmi stream and Thamnos are different from all other halo substructures.

Accepted for publication in MNRAS. The revised version contains a detailed comparison of the chemical composition of Heracles against Aurora and its inner halo in situ counterparts as well as a revised discussion of the chemistry of various Sequoia samples in contrast with Gaia-Enceladus/Sausage

References in corpus (51)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• galpy: A Python Library for Galactic Dynamics
• The mass distribution and gravitational potential of the Milky Way
• The GALAH Survey: Scientific Motivation
• The GALAH+ Survey: Third Data Release
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• 4MOST: Project overview and information for the First Call for Proposals
• Target Selection for the SDSS-IV APOGEE-2 Survey
• The exotic chemical composition of the Sagittarius dwarf Spheroidal galaxy
• The APOGEE red-clump catalog: Precise distances, velocities, and high-resolution elemental abundances over a large area of the Milky Way's disk
• Metallicity gradients in local field star-forming galaxies: Insights on inflows, outflows, and the coevolution of gas, stars and metals
• Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
• Gaia Early Data Release 3: Summary of the contents and survey properties
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Reverse engineering the Milky Way
• The APOGEE Data Release 16 Spectral Line List
• Disentangling the Galactic Halo with APOGEE: I. Chemical and Kinematical Investigation of Distinct Metal-Poor Populations
• Substructure in Tidal Streams; Tributaries in the Anticenter Ring
• Discovery of a New, Polar-Orbiting Debris Stream in the Milky Way Stellar Halo
• The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage
• Tracing Sagittarius Structure with SDSS and SEGUE Imaging and Spectroscopy
• The last breath of the Sagittarius dSph
• Weighing the stellar constituents of the Galactic halo with APOGEE red giant stars
• Origin of the excess of high-energy retrograde stars in the Galactic halo
• Selecting accreted populations: metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations
• The Chemical Compositions of Accreted and {\it in situ} Galactic Globular Clusters According to SDSS/APOGEE
• Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
• A Sequoia in the Garden: FSR 1758 - Dwarf Galaxy or Giant Globular Cluster?
• A Low-Mass Stellar-Debris Stream Associated with a Globular Cluster Pair in the Halo
• The GALAH Survey: Chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 and $Gaia$ eDR3
• APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
• Elevated r-process enrichment in Gaia Sausage and Sequoia
• The Accreted Nuclear Clusters of the Milky Way
• Metallicity and $\alpha$-element Abundance Gradients along the Sagittarius Stream as Seen by APOGEE
• A massive mess: When a large dwarf and a Milky Way-like galaxy merge
• Evidence from Disrupted Halo Dwarfs that $r$-process Enrichment via Neutron Star Mergers is Delayed by $\gtrsim 500$ Myrs
• An all-sky proper motion map of the Sagittarius stream using Gaia DR2
• Stellar Characterization of M-dwarfs from the APOGEE Survey: A Calibrator Sample for the M-dwarf Metallicities
• The Kinematic Properties of Milky Way Stellar Halo Populations
• Identifying Sagittarius Stream Stars By Their APOGEE Chemical Abundance Signatures
• High-precision chemical abundances of Galactic building blocks. The distinct chemical abundance sequence of Sequoia
• The S2 Stream: the shreds of a primitive dwarf galaxy
• The detailed chemical abundance patterns of accreted halo stars from the optical to infrared
• Icarus: a Flat and Fast Prograde Stellar Stream in the Milky Way disk
• High-precision chemical abundances of Galactic building blocks. II. Revisiting the chemical distinctness of the Helmi streams
• R-process-rich stellar streams in the Milky Way
• A homogeneous comparison between the chemical composition of the Large Magellanic Cloud and the Sagittarius dwarf galaxy
• A Blueprint for the Milky Way's Stellar Populations. III. Spatial Distributions and Population Fractions of Local Halo Stars
• G112-43/44: A metal-poor binary star with a unique chemical composition and kinematics like the Helmi streams

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