Chemodynamical Modelling of the Galactic Bulge and Bar

Abstract

We present the first self-consistent chemodynamical model fitted to reproduce data for the galactic bulge, bar and inner disk. We extend the Made-to-Measure method to an augmented phase-space including the metallicity of stars, and show its first application to the bar region of the Milky Way. Using data from the ARGOS and APOGEE (DR12) surveys, we adapt the recent dynamical model from Portail et al. to reproduce the observed spatial and kinematic variations as a function of metallicity, thus allowing the detailed study of the 3D density distributions, kinematics and orbital structure of stars in different metallicity bins. We find that metal-rich stars with [Fe/H] > -0.5 are strongly barred and have dynamical properties that are consistent with a common disk origin. Metal-poor stars with [Fe/H] < -0.5 show strong kinematic variations with metallicity, indicating varying contributions from the underlying stellar populations. Outside the central kpc, metal-poor stars are found to have the density and kinematics of a thick disk while in the inner kpc, evidence for an extra concentration of metal-poor stars is found. Finally, the combined orbit distributions of all metallicities in the model naturally reproduce the observed vertex deviations in the bulge. This paper demonstrates the power of Made-to-Measure chemodynamical models, that when extended to other chemical dimensions will be very powerful tools to maximize the information obtained from large spectroscopic surveys such as APOGEE, GALAH and MOONS.

Accepted for publication by MNRAS. 20 pages, 17 figures

References in corpus (20)

• Improving PARSEC models for very low mass stars
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• The Structure of the Milky Way's Bar Outside the Bulge
• Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
• Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
• Dynamical masses of early-type galaxies at z~2: Are they truly superdense?
• The Gaia-ESO Survey: metallicity and kinematic trends in the Milky Way bulge
• ARGOS II: The Galactic Bulge Survey
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• The Bulge Radial Velocity Assay (BRAVA): I. Techniques and a Rotation Curve
• Dearth of dark matter or massive dark halo? Mass-shape-anisotropy degeneracies revealed by NMAGIC dynamical models of the elliptical galaxy NGC 3379
• Dark matter content and internal dynamics of NGC 4697: NMAGIC particle models from slit data and planetary nebulae velocities
• The long Galactic bar as seen by UKIDSS Galactic Plane Survey
• Peanuts, brezels and bananas: food for thought on the orbital structure of the Galactic bulge
• Why the Milky Way's bulge is not only a bar formed from a cold thin disk
• Mapping a stellar disk into a boxy bulge: The outside-in part of the Milky Way bulge formation
• The Next Generation Virgo cluster Survey. V. modelling the dynamics of M87 with the Made-to-Measure method
• Evidence of a Metal Rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
• The Stellar Halo in the Inner Milky Way: Predicted Shape and Kinematics

Cited by in corpus (51)

• Chemodynamical history of the Galactic Bulge
• Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way's quiescent merger history and in-situ bulge
• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Signatures of resonance and phase mixing in the Galactic disc
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• Self-consistent construction of virialized wave dark matter halos
• APOGEE DR14/DR15 Abundances in the Inner Milky Way
• The stellar mass distribution of the Milky Way's bar: an analytic model
• The Bar and Spiral Arms in the Milky Way: Structure and Kinematics
• Formation, vertex deviation and age of the Milky Way's bulge: input from a cosmological simulation with a late-forming bar
• Sculpting Andromeda -- made-to-measure models for M31's bar and composite bulge: dynamics, stellar and dark matter mass
• The Bulge Metallicity Distribution from the APOGEE Survey
• Trojans in the Solar Neighborhood
• Disentangling the formation history of galaxies via population-orbit superposition: method validation
• Galactic Rotation from Cepheids with Gaia DR2 and Effects of Non-Axisymmetry
• Relations among structural parameters in barred galaxies with a direct measurement of bar pattern speed
• The GALAH Survey: Stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere and metallicity
• The Hercules stream as seen by APOGEE-2 South
• The Milky Way's bulge star formation history as constrained from its bimodal chemical abundance distribution
• The stellar populations of the central region of M31
• Blanco DECam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results
• The central velocity dispersion of the Milky Way bulge
• Stars behind bars II: A cosmological formation scenario for the Milky Way's central stellar structure
• The disc origin of the Milky Way bulge: On the necessity of the thick disc
• The structural evolution of galaxies with both thin and thick discs
• Simulating the Legacy Survey of Space and Time stellar content with TRILEGAL
• A2A: 21,000 bulge stars from the ARGOS survey with stellar parameters on the APOGEE scale
• The Milky Way's middle-aged inner ring
• Effects of the Central Mass Concentration on Bar Formation in Disk Galaxies
• First results from a large-scale proper motion study of the Galactic Centre
• Searching for a kinematic signature of the moderately metal-poor stars in the Milky Way bulge using N-body simulations
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Probing the Milky Way stellar and brown dwarf initial mass function with modern microlensing observations
• The initial mass function of stars and the star-formation rates of galaxies
• Blanco DECam Bulge Survey (BDBS) V. Cleaning the foreground populations from Galactic bulge colour-magnitude diagrams using Gaia EDR3
• Signatures of the Galactic bar on stellar kinematics unveiled by APOGEE
• A spectroscopic map of the Galactic centre -- Observations and resolved stars
• Unravelling stellar populations in the Andromeda Galaxy
• Rediscovering the Milky Way with orbit superposition approach and APOGEE data I. Method validation
• Basis function expansions for galactic dynamics: Spherical versus cylindrical coordinates
• Predicted Trends in Milky Way Bulge Proper Motion Rotation Curves: future Prospects for HST and LSST
• Metallicity Properties of the Galactic Bulge Stars Near and Far: Expectations from the Auriga Simulation
• From moving groups to star formation in the Solar Neighborhood
• Resolving local and global kinematic signatures of satellite mergers with billion particle simulations
• Signatures of the Galactic bar in high-order moments of proper motions measured by Gaia
• The barred inner Milky Way: dynamical models from surveys
• The Two-infall Model Revisited: Constraints on Milky Way Bulge Assembly from >30,000 Galactic Chemical Evolution Models and Machine Learning
• Dynamical Models of the Milky Way in Action Space with LAMOST DR8 and GAIA EDR3
• Distribution functions for spheroids
• Closing remarks and Outlook
• The chemodynamical memory of a major merger in a NIHAO-UHD Milky Way analogue -- I. A golden thread through time and space