A high fidelity Milky Way simulation with Kraken, Gaia-Enceladus, and Sequoia analogues: clues to their accretion histories

Abstract

Within a simulated Milky Way-like galaxy, we identify and analyse analogues of the Gaia-Enceladus (GE), Kraken and Sequoia mergers that each matches remarkably well observational results, including in velocity and chemical abundance space, and their distributions in the $j_z$-Energy plane. The Kraken analogue is the earliest merger and has the highest total mass ratio. Consistent with previous studies, it is chemically indistinguishable from old in-situ stars at the time of its accretion. The GE and Sequoia analogue events accrete at similar times in our simulation, both along filaments but from opposite sides of the main galaxy. The mean stellar ages of the GE and Sequoia analogues are both similar and, from our simulation results, we see that they can be separate entities and still naturally reproduce the observed properties of their stellar remnants at the present day, including the significant retrograde velocities of the Sequoia analogue remnant stars and the difference in the tracks of the two galaxies through chemical abundance space. Our results provide supporting information about the properties of these three merger events, and show for the first time that they can all be reproduced with a fully cosmological simulation, providing a possible self consistent evolutionary pathway for the Milky Way's formation.

arXiv comment8 pages, 6 figures, published in MNRAS (accepted version)

References in corpus (60)

• Array Programming with NumPy
• Galactic Stellar and Substellar Initial Mass Function
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• The Global Schmidt Law in Star Forming Galaxies
• Radiative Transfer in a Clumpy Universe: II. The Utraviolet Extragalactic Background
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The New Galaxy: Signatures of its Formation
• Co-formation of the Galactic disc and the stellar halo
• Ahf: Amiga's Halo Finder
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Gasoline: An adaptable implementation of TreeSPH
• Kinematics of Metal-Poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Non-Kinematically Selected Stars
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Building up the Stellar Halo of the Galaxy
• The evolution substructure I: a new identification method
• Origin of the system of globular clusters in the Milky Way
• Making Galaxies in a Cosmological Context: The Need for Early Stellar Feedback
• The Enrichment of the Intergalactic Medium with Adiabatic Feedback I: Metal Cooling and Metal Diffusion
• Streams, substructures and the early history of the Milky Way
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• 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 Dual Origin of Stellar Halos
• The Biggest Splash
• Fossil Signatures of Ancient Accretion Events in the Halo
• The origin of accreted stellar halo populations in the Milky Way using APOGEE, $\text{Gaia}$, and the EAGLE simulations
• A Prescription for Building the Milky Way's Halo from Disrupted Satellites
• The birth of the Milky Way as uncovered by accurate stellar ages with Gaia
• Kraken reveals itself -- the merger history of the Milky Way reconstructed with the E-MOSAICS simulations
• Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history
• Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
• 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
• Quenching and ram pressure stripping of simulated Milky Way satellite galaxies
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• Two distinct halo populations in the solar neighborhood. II. Evidence from stellar abundances of Mn, Cu, Zn, Y, and Ba
• Contributions to the accreted stellar halo: an atlas of stellar deposition
• MaGICC Disks: Matching Observed Galaxy Relationships Over a Wide Stellar Mass Range
• Reconstructing the Last Major Merger of the Milky Way with the H3 Survey
• Cosmological Galaxy Formation Simulations Using SPH
• Accretion relicts in the solar neighbourhood: debris from omegaCen's parent galaxy
• The chemical characterisation of halo substructure in the Milky Way based on APOGEE
• The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage
• Sausage & Mash: The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus-Sausage merger
• A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
• The last breath of the Sagittarius dSph
• Origin of the excess of high-energy retrograde stars in the Galactic halo
• Age dating of an early Milky Way merger via asteroseismology of the naked-eye star $\nu$ Indi
• Galactic Halo Stars in Phase Space :A Hint of Satellite Accretion?
• Chemo-dynamics of outer halo dwarf stars, including \textit{Gaia}-Sausage and \textit{Gaia}-Sequoia candidates
• GASTRO library I: the simulated chemodynamical properties of several GSE-like stellar halos
• A massive mess: When a large dwarf and a Milky Way-like galaxy merge
• A panoramic landscape of the Sagittarius stream in Gaia DR2 revealed with the STREAMFINDER spyglass
• Predicting accreted satellite galaxy masses and accretion redshifts based on globular cluster orbits in the E-MOSAICS simulations
• High-precision chemical abundances of Galactic building blocks. The distinct chemical abundance sequence of Sequoia
• Pericentric passage-driven star formation in satellite galaxies and their hosts: CLUES from Local Group simulations
• Origin of the Metallicity Distribution in the Thick Disc
• Probing the Galactic Halo with RR Lyrae Stars. II. The Substructures of the Milky Way
• The observable properties of galaxy accretion events in Milky Way-like galaxies in the FIRE-2 cosmological simulations
• Explaining the chemical trajectories of accreted and in-situ halo stars of the Milky Way
• Live Fast, Die $\alpha$-Enhanced: The Mass-Metallicity-$\alpha$ Relation of the Milky Way's Disrupted Dwarf Galaxies

Cited by in corpus (4)

• Milky Way-est: Cosmological Zoom-in Simulations with Large Magellanic Cloud and Gaia-Sausage-Enceladus Analogs
• Formation of Transitional cE/UCD Galaxies through Massive/Dwarf Disc Galaxy Mergers
• How well can we unravel the accreted constituents of the Milky Way stellar halo? A test on cosmological hydrodynamical simulations
• Cosmological Simulations of Stellar Halos with Gaia Sausage-Enceladus Analogues: Two Sausages, One Bun?