Origin of chemically distinct discs in the Auriga cosmological simulations

Abstract

The stellar disk of the Milky Way shows complex spatial and abundance structure that is central to understanding the key physical mechanisms responsible for shaping our Galaxy. In this study, we use six very high resolution cosmological zoom simulations of Milky Way-sized haloes to study the prevalence and formation of chemically distinct disc components. We find that our simulations develop a clearly bimodal distribution in the $[\alpha /Fe]$ -- $[Fe/H]$ plane. We find two main pathways to creating this dichotomy which operate in different regions of the galaxies: a) an early ($z>1$) and intense high-$[\alpha /Fe]$ star formation phase in the inner region ($R\lesssim 5$ kpc) induced by gas-rich mergers, followed by more quiescent low-$[\alpha /Fe]$ star formation; and b) an early phase of high-$[\alpha /Fe]$ star formation in the outer disc followed by a shrinking of the gas disc owing to a temporarily lowered gas accretion rate, after which disc growth resumes. In process b), a double-peaked star formation history around the time and radius of disc shrinking accentuates the dichotomy. If the early star formation phase is prolonged (rather than short and intense), chemical evolution proceeds as per process a) in the inner region, but the dichotomy is less clear. In the outer region, the dichotomy is only evident if the first intense phase of star formation covers a large enough radial range before disc shrinking occurs; otherwise, the outer disc consists of only low-$[\alpha /Fe]$ sequence stars. We discuss the implication that both processes occurred in the Milky Way.

12 pages, MNRAS accepted

References in corpus (23)

• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc
• Tracing chemical evolution over the extent of the Milky Way's Disk with APOGEE Red Clump Stars
• The age-metallicity structure of the Milky Way disk
• Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
• Constraining the thick disc formation scenario of the Milky Way
• The Structure and Dynamical Evolution of the Stellar Disk of a Simulated Milky Way-Mass Galaxy
• The effect of radial migration on galactic disks
• The AMBRE Project: chemical evolution models for the Milky Way thick and thin discs
• A radial age gradient in the geometrically thick disk of the Milky Way
• Two Disk Components from a Gas Rich Disk-Disk Merger
• Impact of radial migration on stellar and gas radial metallicity distribution
• Properties of HI discs in the Auriga cosmological simulations
• The relationship between mono-abundance and mono-age stellar populations in the Milky Way disk
• Diffuse gas properties and stellar metallicities in cosmological simulations of disc galaxy formation
• Physical properties of the interstellar medium using high-resolution Chandra spectra: O K-edge absorption
• The Rotation-Metallicity Relation for the Galactic Disk as Measured in the Gaia DR1 TGAS and APOGEE Data
• Cardinal kinematics: I. Rotation fields of the APOGEE Survey
• Metallicity Gradient of the Thick Disc Progenitor at High Redshift
• The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data
• The Radial Distribution of Mono-Metallicity Populations in the Galactic Disk as Evidence for Two-Phase Disk Formation

Cited by in corpus (64)

• Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs
• The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage
• The Hestia project: simulations of the Local Group
• High-precision abundances of elements in solar-type stars. Evidence of two distinct sequences in abundance-age relations
• The GALAH survey: tracing the Galactic disk with Open Clusters
• Gas accretion and galactic fountain flows in the Auriga cosmological simulations: angular momentum and metal re-distribution
• APOGEE DR16: a multi-zone chemical evolution model for the Galactic disc based on MCMC methods
• Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
• The bursty origin of the Milky Way thick disc
• The Stellar Halo of the Galaxy is Tilted & Doubly Broken
• Characterizing epochs of star formation across the Milky Way disc using age-metallicity distributions of GALAH stars
• Dark matter halo shapes in the Auriga simulations
• Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc
• On the origin of the Galactic thin and thick discs, their abundance gradients and the diagnostic potential of their abundance ratios
• The evolution of CNO elements in galaxies
• The Milky Way tomography with APOGEE: intrinsic density distribution and structure of mono-abundance populations
• Quantifying radial migration in the Milky Way: Inefficient over short timescales but essential to the very outer disc beyond ~15 kpc
• The challenge of simultaneously matching the observed diversity of chemical abundance patterns in cosmological hydrodynamical simulations
• Chronology of our Galaxy from Gaia Colour-Magnitude Diagram-fitting (ChronoGal). I. The formation and evolution of the thin disk from the Gaia Catalogue of Nearby Stars
• Radial structure and formation of the Milky Way disc
• The impact of magnetic fields on cosmological galaxy mergers. I: Reshaping gas and stellar discs
• The distribution of [$\alpha$/Fe] in the Milky Way disc
• The [α/Fe]-[Fe/H] relation in the E-MOSAICS simulations: its connection to the birth place of globular clusters and the fraction of globular cluster field stars in the bulge
• The impact of early massive mergers on the chemical evolution of Milky Way-like galaxies: insights from NIHAO-UHD simulations
• APOGEE [C/N] Abundances Across the Galaxy: Migration and Infall from Red Giant Ages
• Chemical Evolution with Radial Mixing Redux: Extending beyond the Solar Neighborhood
• [Mg/Fe] ratios in the solar neighbourhood: stellar yields and chemical evolution scenarios
• Chemical evolution of disc galaxies from cosmological simulations
• (Re)mind the gap: a hiatus in star formation history unveiled by APOGEE DR17
• Baryonic effects on the detectability of annihilation radiation from dark matter subhaloes around the Milky Way
• On the effects of the Initial Mass Function on Galactic chemical enrichment
• The stellar halo in Local Group Hestia simulations III. Chemical abundance relations for accreted and in-situ stars
• Mapping radial abundance gradients with Gaia-ESO open clusters: Evidence of recent gas accretion in the Milky Way disk
• Exploring the diversity and similarity of radially anisotropic Milky Way-like stellar haloes: implications for disrupted dwarf galaxy searches
• The imprint of clump formation at high redshift. II. The chemistry of the bulge
• ISM metallicity variations across spiral arms in disk galaxies: the impact of local enrichment and gas migration in the presence of radial metallicity gradient
• Disc dichotomy signature in the vertical distribution of [Mg/Fe] and the delayed gas infall scenario
• Dark matter annihilation and the Galactic Centre Excess
• Buckling bars in nearly face-on galaxies observed with MaNGA
• Stellar populations and origin of thick disks in AURIGA simulations
• The impact of magnetic fields on cosmological galaxy mergers -- II. Modified angular momentum transport and feedback
• Chemodynamical Analysis of Metal-rich High-eccentricity Stars in the Milky Way's Disk
• Stellar migration in the Auriga simulations
• Exploring the Evolution of Massive Clumps in Simulations that Reproduce the Observed Milky Way α-element Abundance Bimodality
• Galactic r-process abundance feature shaped by radial migration
• Chronology of our Galaxy from Gaia colour-magnitude diagram fitting (ChronoGal) II. Unveiling the formation and evolution of the kinematically selected Thick and Thin Discs
• An observational testbed for cosmological zoom-in simulations: constraining stellar migration in the solar cylinder using asteroseismology
• Predictions for Complex Distributions of Stellar Elemental Abundances in Low-Mass Galaxies
• AuriDESI: Mock Catalogues for the DESI Milky Way Survey
• Metallicity Properties of the Galactic Bulge Stars Near and Far: Expectations from the Auriga Simulation
• Anatomy of galactic star formation history: Roles of different modes of gas accretion, feedback, and recycling
• Stellar Migration and Chemical Enrichment in the Milky Way Disc: A Hybrid Model
• The Milky Way in context: The formation of galactic discs and chemical sequences from a cosmological perspective
• Relatively young thick disks in star-forming late-type galaxies
• Applying machine learning to Galactic Archaeology: how well can we recover the origin of stars in Milky Way-like galaxies?
• Inferring Galactic Parameters from Chemical Abundances: A Multi-Star Approach
• Modelling the chemical evolution of the Milky Way
• The Stellar Chemical Abundances of Simulated Massive Galaxies at $z=2$
• Neutron-capture elements record the ordered chemical evolution of the disc over time
• A Tilt in the Dark Matter Halo of the Galaxy
• The chemodynamical memory of a major merger in a NIHAO-UHD Milky Way analogue -- I. A golden thread through time and space
• J-PLUS Reconstructing the Milky Way Disc's star formation history with twelve-filter photometry
• Dynamical properties of high-[Mg/Fe] stars in the Milky Way bar region
• Machine Learning for Galactic Archaeology: A chemistry-based neural network method for identification of accreted disc stars