Panchromatic Hubble Andromeda Treasury XII. Mapping Stellar Metallicity Distributions in M31

Abstract

We present a study of spatial variations in the metallicity of old red giant branch stars in the Andromeda galaxy. Photometric metallicity estimates are derived by interpolating isochrones for over seven million stars in the Panchromatic Hubble Andromeda Treasury (PHAT) survey. This is the first systematic study of stellar metallicities over the inner 20 kpc of Andromeda's galactic disk. We see a clear metallicity gradient of $-0.020\pm 0.004$ dex/kpc from $\sim 4-20$ kpc assuming a constant RGB age. This metallicity gradient is derived after correcting for the effects of photometric bias and completeness and dust extinction and is quite insensitive to these effects. The unknown age gradient in M31's disk creates the dominant systematic uncertainty in our derived metallicity gradient. However, spectroscopic analyses of galaxies similar to M31 show that they typically have small age gradients that make this systematic error comparable to the 1$\sigma$ error on our metallicity gradient measurement. In addition to the metallicity gradient, we observe an asymmetric local enhancement in metallicity at radii of 3-6 kpc that appears to be associated with Andromeda's elongated bar. This same region also appears to have an enhanced stellar density and velocity dispersion.

13 pages, 12 figures. Accepted for publication by AJ

References in corpus (45)

• Astropy: A Community Python Package for Astronomy
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation
• Improving PARSEC models for very low mass stars
• Numerical Methods of Star Formation History Measurement and Applications to Seven Dwarf Spheroidals
• A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• The Panchromatic Hubble Andromeda Treasury
• The CALIFA survey across the Hubble sequence: Spatially resolved stellar population properties in galaxies
• The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties
• CALIFA: a diameter-selected sample for an integral field spectroscopy galaxy survey
• The Panchromatic Hubble Andromeda Treasury X. Ultraviolet to Infrared Photometry of 117 Million Equidistant Stars
• Structure of Disk Dominated Galaxies: II. Color Gradients and Stellar Population Models
• Stellar Population gradients in galaxy discs from the CALIFA survey
• The flat oxygen abundance gradient in the extended disk of M83
• The star formation history of CALIFA galaxies: Radial structures
• The Luminosity Profile and Structural Parameters of the Andromeda Galaxy
• The Metal-Poor Halo of the Andromeda Spiral Galaxy (M31)
• Chemical Cartography with APOGEE: Large-scale Mean Metallicity Maps of the Milky Way
• Signatures of radial migration in barred galaxies: Azimuthal variations in the metallicity distribution of old stars
• Metallicity Gradients in the Milky Way Disk as Observed by the SEGUE Survey
• Dusty waves on a starry sea: the mid-infrared view of M31
• Stellar Population and Kinematic Profiles in Spiral Bulges & Disks: Population Synthesis of Integrated Spectra
• Chemical abundances in M31 from HII regions
• Phase-Space Distributions of Chemical Abundances in Milky Way-type Galaxy Halos
• The Detection of Inside-out Disk Growth in M33
• The Gaia-ESO Survey: the chemical structure of the Galactic discs from the first internal data release
• Revised bolometric corrections and interstellar extinction coefficients for the ACS and WFPC2 photometric systems
• The ACS Nearby Galaxy Survey Treasury V. Radial Star Formation History of NGC 300
• Unravelling the mystery of the M31 bar
• The old and heavy bulge of M31 I. Kinematics and stellar populations
• The Panchromatic Hubble Andromeda Treasury VIII: A Wide-Area, High-Resolution Map of Dust Extinction in M31
• Global Properties of M31's Stellar Halo from the SPLASH Survey: II. Metallicity Profile
• The Andromeda Project. I. Deep HST-WFPC2 V,I photometry of 16 fields toward the disk and the halo of the M31 galaxy. Probing the stellar content and metallicity distribution
• A clear age-velocity dispersion correlation in Andromeda's stellar disk
• The Extended Star Formation History of the Andromeda Spheroid at 35 Kpc on the Minor Axis
• Chemical gradients in the Milky Way from the RAVE data. II. Giant stars
• A New Approach to Detailed Structural Decomposition from the SPLASH and PHAT Surveys: Kicked-up Disk Stars in the Andromeda Galaxy?
• Abundances of PNe in the Outer Disk of M31
• The Formation and Evolution of Virgo Cluster Galaxies - II. Stellar Populations
• Deep near-infrared imaging of W3 Main: constraints on stellar cluster formation
• The Recent Stellar Archeology of M31 - The Nearest Red Disk Galaxy
• Andromeda Optical and Infrared Disk Survey I. New Insights in Wide-Field Near-IR Surface Photometry

Cited by in corpus (30)

• The Structure and Dynamical Evolution of the Stellar Disk of a Simulated Milky Way-Mass Galaxy
• A census of symbiotic stars in the 2MASS, WISE and Gaia surveys
• VINTERGATAN II: the history of the Milky Way told by its mergers
• The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) I. Ultraviolet to Infrared Photometry of 22 Million Stars in M33
• The information content of stellar halos: Stellar population gradients and accretion histories in early-type Illustris galaxies
• The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type: A tracer of globular cluster formation and evolution
• Unusual integrated metallicity profile of our Milky Way
• Elemental Abundances in M31: A Comparative Analysis of Iron and Alpha Element Abundances in the Outer Disk, Giant Stellar Stream, and Inner Halo of M31
• The Red and Featureless Outer Disks of Nearby Spiral Galaxies
• The stellar populations of the central region of M31
• A Dramatic Decrease in Carbon Star Formation in M31
• The survey of planetary nebulae in Andromeda (M31). IV. Radial oxygen and argon abundance gradients of the thin and thicker disc
• Spatially Resolved Metal Loss from M31
• Young Accreting Compact Objects in M31: The Combined Power of NuSTAR, Chandra, and Hubble
• Pixel Color Magnitude Diagrams for Semi-Resolved Stellar Populations: The Star Formation History of Regions within the Disk and Bulge of M31
• Comparing Chandra and Hubble in the Northern Disk of M31
• Multiwavelength Characterization of the High Mass X-ray Binary Population of M31
• Elemental abundances in M31: Individual and Coadded Spectroscopic [Fe/H] and [α/Fe] throughout the M31 Halo with SPLASH
• A Census of Thermally-Pulsing AGB stars in the Andromeda Galaxy and a First Estimate of their Contribution to the Global Dust Budget
• 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
• Kinematics and Metallicity of Red Giant Branch Stars in the Northeast Shelf of M31
• Unravelling stellar populations in the Andromeda Galaxy
• New insights into the use of Ultra Long Period Cepheids as cosmological standard candles
• The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated Light Spectroscopy
• Resolved SPLASH Chemodynamics in Andromeda's PHAT Stellar Halo and Disk: On the Nature of the Inner Halo Along the Major Axis
• 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
• Emission-line stars in M31 from the SPLASH and PHAT surveys
• On the Use of Field RR Lyrae as Galactic Probes -- VIII. Early Formation of the Galactic Spheroid
• Towards Understanding the Milky Way's Typicality: Assessing the Chemodynamics of M31's Bulge & Bar, Thick & Thin Discs