Unravelling stellar populations in the Andromeda Galaxy

Abstract

To understand the history and formation mechanisms of galaxies it is crucial to determine their current multidimensional structure. Here we focus on stellar population properties, such as metallicity and [$\alpha$/Fe] enhancement. We devise a new technique to recover the distribution of these parameters using spatially resolved, line-of-sight averaged data. Our chemodynamical method is based on the made-to-measure (M2M) framework and results in an $N$-body model for the abundance distribution. We test our method on a mock data set and find that the radial and azimuthal profiles are well-recovered, however only the overall shape of the vertical profile matches the true profile. We apply our procedure to spatially resolved maps of mean [Z/H] and [$\alpha$/Fe] for the Andromeda Galaxy, using an earlier barred dynamical model of M31. We find that the metallicity is enhanced along the bar, with possible maxima at the ansae. In the edge-on view the [Z/H] distribution has an X shape due to the boxy/peanut bulge; the average vertical metallicity gradient is equal to $-0.133\pm 0.006$ dex/kpc. We identify a metallicity-enhanced ring around the bar, which also has relatively lower [$\alpha$/Fe]. The highest [$\alpha$/Fe] is found in the centre, due to the classical bulge. Away from the centre, the $\alpha$-overabundance in the bar region increases with height, which could be an indication of a thick disc. We argue that the galaxy assembly resulted in a sharp peak of metallicity in the central few hundred parsecs and a more gentle negative gradient in the remaining disc, but no [$\alpha$/Fe] gradient. The formation of the bar lead to the re-arrangement of the [Z/H] distribution, causing a flat gradient along the bar. Subsequent star formation close to the bar ends may have produced the metallicity enhancements at the ansae and the [Z/H] enhanced lower-$\alpha$ ring.

arXiv comment20 pages, 17 figures, 1.9MB, accepted to A&A

References in corpus (106)

• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• The epochs of early-type galaxy formation as a function of environment
• Adaptive spatial binning of integral-field spectroscopic data using Voronoi tessellations
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Morphology, photometry and kinematics of N-body bars. I Three models with different halo central concentrations
• Andromeda's Dust
• The Secular Evolution of Disk Structural Parameters
• Evolution of the Bar Fraction in COSMOS: Quantifying the Assembly of the Hubble Sequence
• A New Mechanism for Radial Migration in Galactic Disks: Spiral-Bar Resonance Overlap
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• Secular Evolution in Disk Galaxies
• Bulgeless Giant Galaxies Challenge our Picture of Galaxy Formation by Hierarchical Clustering
• Reconstructing the stellar mass distributions of galaxies using S4G IRAC 3.6 and 4.5 micron images: II. The conversion from light to mass
• Dissipation and Extra Light in Galactic Nuclei: IV. Evolution in the Scaling Relations of Spheroids
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• Resolving galaxies in time and space: I: Applying STARLIGHT to CALIFA data cubes
• Stellar Population gradients in galaxy discs from the CALIFA survey
• Flux-calibrated stellar population models of Lick absorption-line indices with variable element abundance ratios
• Made-to-measure N-body systems
• Star formation history of barred disc galaxies
• The Dependence of Bar Frequency on Galaxy Mass, Colour, and Gas Content -- and Angular Resolution -- in the Local Universe
• Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
• Orbital dynamics of three-dimensional bars: I. The backbone of 3D bars. A fiducial case
• Separation of Stellar Populations by an Evolving Bar: Implications for the Bulge of the Milky Way
• Signatures of radial migration in barred galaxies: Azimuthal variations in the metallicity distribution of old stars
• Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way's quiescent merger history and in-situ bulge
• On the interpretation of age and chemical composition of composite stellar populations determined with line-strength indices
• Galaxy Zoo: An independent look at the evolution of the bar fraction over the last eight billion years from HST-COSMOS
• Dusty waves on a starry sea: the mid-infrared view of M31
• Composite Bulges: The Coexistence of Classical Bulges and Disky Pseudobulges in S0 and Spiral Galaxies
• A 2-3 billion year old major merger paradigm for the Andromeda galaxy and its outskirts
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• Panoramic GALEX FUV and NUV imaging of M31 and M33
• Galaxy Zoo: The Environmental Dependence of Bars and Bulges in Disc Galaxies
• SDSS-IV MaNGA: environmental dependence of stellar age and metallicity gradients in nearby galaxies
• Time Inference with MUSE in Extragalactic Rings (TIMER): Properties of the Survey and High-Level Data Products
• Resolving galaxies in time and space: II: Uncertainties in the spectral synthesis of datacubes
• Peanuts at an Angle: Detecting and Measuring the Three-Dimensional Structure of Bars in Moderately Inclined Galaxies
• Spiral-induced velocity and metallicity patterns in a cosmological zoom simulation of a Milky Way-sized galaxy
• Unravelling the mystery of the M31 bar
• The Fornax 3D project: unveiling the thick disk origin in FCC 170: signs of accretion?
• Bars rejuvenating bulges? Evidence from stellar population analysis
• Dark matter content and internal dynamics of NGC 4697: NMAGIC particle models from slit data and planetary nebulae velocities
• The Panchromatic Hubble Andromeda Treasury VIII: A Wide-Area, High-Resolution Map of Dust Extinction in M31
• Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy
• Stellar Populations in Bulges
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• Bulge Formation via Mergers in Cosmological Simulations
• Bars and Dark Matter Halo Cores
• Bulge growth through disk instabilities in high-redshift galaxies
• On the deprojection of axisymmetric bodies
• A Vertical Resonance Heating Model for X- or Peanut-Shaped Galactic Bulges
• The H alpha Galaxy Survey VII. The spatial distribution of star formation within disks and bulges
• Three Mechanisms for Bar Thickening
• Chemodynamical Modelling of the Galactic Bulge and Bar
• Combining Stellar Populations with Orbit-Superposition Dynamical Modelling - the Formation History of the Lenticular Galaxy NGC 3115
• Instabilities of a family of oblate stellar spheroids
• The oxygen abundance gradients in the gas discs of galaxies in the EAGLE simulation
• Study of the stellar line-strength indices and kinematics along bars
• Probing recent star formation with absorption-line strengths in hierarchical models and observations
• Metallicity gradients through disk Instability: A simple model for the Milky Way's boxy bulge
• An Observational Guide to Identifying Pseudobulges and Classical Bulges in Disk Galaxies
• The formation of the [alpha/Fe] radial gradients in the stars of elliptical galaxies
• A unified framework for the orbital structure of bars and triaxial ellipsoids
• The Metallicity and Elemental Abundance Gradients of Simulated Galaxies, and their Environmental Dependence
• Study of stellar populations in the bulges of barred galaxies
• The Fornax 3D project: Thick disks in a cluster environment
• Formation, vertex deviation and age of the Milky Way's bulge: input from a cosmological simulation with a late-forming bar
• Origin of the high v_los feature in the Galactic bar
• Stellar Population Gradients in Bulges along the Hubble Sequence: II. Relations with Galaxy Properties
• Sculpting Andromeda -- made-to-measure models for M31's bar and composite bulge: dynamics, stellar and dark matter mass
• Using NMAGIC to probe the dark matter halo and orbital structure of the X-ray bright, massive elliptical galaxy, NGC 4649
• The Metallicity Distribution of the Milky Way Bulge
• A single-merger scenario for the formation of the giant stream and the warp of M31
• The outside-in formation of elliptical galaxies
• Boxy/peanut/X bulges, barlenses and the thick part of galactic bars: What are they and how did they form?
• Disentangling the formation history of galaxies via population-orbit superposition: method validation
• Revealing the cosmic evolution of boxy/peanut-shaped bulges from HST COSMOS and SDSS
• Panchromatic Hubble Andromeda Treasury XII. Mapping Stellar Metallicity Distributions in M31
• Redistribution of Stars and Gas in the Star Formation Deserts of Barred Galaxies
• The stellar kinematics and populations of boxy bulges: cylindrical rotation and vertical gradients
• A Global Star Forming Episode in M31 2-4 Gyr Ago
• SDSS-IV MaNGA: Stellar Population Gradients Within Barred Galaxies
• Stellar populations across galaxy bars in the MUSE TIMER project
• The stellar metallicity gradients in galaxy discs in a cosmological scenario
• Stellar metallicity variations across spiral arms in disk galaxies with multiple populations
• The stellar populations of the central region of M31
• Box/peanut-shaped bulges in action space
• The BaLROG project - II. Quantifying the influence of bars on the stellar populations of nearby galaxies
• The Connection between Star Formation and Metallicity Evolution in Barred Spiral Galaxies
• Made-to-measure galaxy models - II Elliptical and Lenticular Galaxies
• Spin-up of massive classical bulges during secular evolution
• SDSS-IV MaNGA: Excavating the fossil record of stellar populations in spiral galaxies
• The Star Formation History in the M31 Bulge
• The orbital structure of a tidally induced bar
• The chemistry of stars in the bar of the Milky Way
• Evidence for non-axisymmetry in M31 from wide-field kinematics of stars and gas
• Type Ia supernovae and the formation history of early-type galaxies
• Secular evolution in action: central values and radial trends in the stellar populations of boxy bulges
• Numerical Simulation of a possible origin of the positive radial metallicity gradient of the thick disk
• Mild evolution of the stellar metallicity gradients of disc galaxies
• Chemo-dynamical modelling with Schwarzschild's method
• Made-to-measure galaxy modelling utilising absorption line strength data
• The validation of made-to-measure method for reconstruction of phase space distribution functions
• The survey of Planetary Nebulae in Andromeda (M31): I. Imaging the disk and halo with MegaCam@CFHT

Cited by in corpus (8)

• The Milky Way's middle-aged inner ring
• The Panchromatic Hubble Andromeda Treasury XX: The Disk of M31 is Thick
• The Non-Axisymmetric Influence: Radius and Angle-Dependent Trends in a Barred Galaxy
• The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated Light Spectroscopy
• Large-scale Hydrodynamical Shocks as the Smoking Gun Evidence for a Bar in M31
• The survey of planetary nebulae in Andromeda (M31) VII. Predictions of a major merger simulation model compared with chemodynamical data of the disc and inner halo substructures
• The Accretion Mode in Sub-Eddington Supermassive Black Holes: Getting into the Central Parsecs of Andromeda
• Towards Understanding the Milky Way's Typicality: Assessing the Chemodynamics of M31's Bulge & Bar, Thick & Thin Discs