The Bulge Metallicity Distribution from the APOGEE Survey

Abstract

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) provides spectroscopic information of regions of the inner Milky Way inaccessible to optical surveys. We present the first large study of the metallicity distribution of the innermost Galactic regions based on homogeneous measurements from the SDSS Data Release 12 for 7545 red giant stars within 4.5 kpc of the Galactic center, with the goal to shed light on the structure and origin of the Galactic bulge. Stellar metallicities are found, through multiple-Gaussian decompositions, to be distributed in several components indicative of the presence of various stellar populations such as the bar, or the thin and the thick disk. A super-solar ([Fe/H]=+0.32) and a solar ([Fe/H]=+0.00) metallicity components, tentatively associated with the thin disk and the Galactic bar, respectively, seem to be the major contributors near the midplane. The solar-metallicity component extends outwards in the midplane but is not observed in the innermost regions. The central regions (within 3 kpc of the Galactic center) reveal, on the other hand, the presence of a significant metal-poor population ([Fe/H] =-0.46), tentatively associated with the thick disk, and which becomes the dominant component far from the midplane ($|Z| > +0.75 kpc). Varying contributions from these different components produce a transition region at +0.5 kpc < |Z| < +1.0 kpc characterized by a significant vertical metallicity gradient.

arXiv comment15 pages, 11 figures

References in corpus (77)

• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Evolution of asymptotic giant branch stars II. Optical to far-infrared isochrones with improved TP-AGB models
• The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 microns Using GLIMPSE Data
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Forming Realistic Late-Type Spirals in a LCDM Universe: The Eris Simulation
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. V. Evidence for a wide age distribution and a complex MDF
• The Secular Evolution of Disk Structural Parameters
• The spatial structure of mono-abundance sub-populations of the Milky Way disk
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• Abundances, Stellar Parameters, and Spectra From the SDSS-III/APOGEE Survey
• The Galactic disk mass-budget : I. stellar mass-function and density
• Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The Structure of the Milky Way's Bar Outside the Bulge
• Our Milky Way as a Pure-Disk Galaxy -- A Challenge for Galaxy Formation
• The Metal Content of Bulge Field Stars from FLAMES-GIRAFFE Spectra. I. Stellar parameters and Iron Abundances
• ARGOS III: Stellar Populations in the Galactic Bulge of the Milky Way
• Two Red Clumps and the X-Shaped Milky Way Bulge
• The formation of disc galaxies in a LCDM universe
• Stellar populations in the Milky Way bulge region : Towards solving the Galactic bulge and bar shapes using 2MASS data
• The Split Red Clump of the Galactic Bulge from OGLE-III
• The metallicity distribution of bulge clump giants in Baade's Window
• Radial mixing and the transition between the thick and thin Galactic discs
• A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc
• Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
• Dynamical Blueprints for Galaxies
• Tracing chemical evolution over the extent of the Milky Way's Disk with APOGEE Red Clump Stars
• Lifting the Dusty Veil With Near- and Mid-Infrared Photometry: I. Description and Applications of the Rayleigh-Jeans Color Excess Method
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
• Chemical Cartography with APOGEE: Large-scale Mean Metallicity Maps of the Milky Way
• Bar Diagnostics in Edge-On Spiral Galaxies. III. N-Body Simulations of Disks
• The SDSS-III APOGEE Spectral Line List for H-band Spectroscopy
• Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
• Constraining the thick disc formation scenario of the Milky Way
• The GIRAFFE Inner Bulge Survey (GIBS) III. Metallicity distributions and kinematics of 26 Galactic bulge fields
• Extreme deconvolution: Inferring complete distribution functions from noisy, heterogeneous and incomplete observations
• The Gaia-ESO Survey: metallicity and kinematic trends in the Milky Way bulge
• New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE survey
• VVV Survey Near-Infrared Photometry of Known Bulge RR Lyrae stars: the Distance to the Galactic Center and Absence of a Barred Distribution of the Metal-Poor Population
• ARGOS II: The Galactic Bulge Survey
• The Bulge Radial Velocity Assay (BRAVA): I. Techniques and a Rotation Curve
• Kinematics at the Edge of the Galactic Bulge: Evidence for Cylindrical Rotation
• Unifying boxy bulge and planar long bar in the Milky Way
• A diversity of progenitors and histories for isolated spiral galaxies
• Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS III. The first global photometric metallicity map of the Galactic bulge
• Constraining the structure and formation of the Galactic bulge from a field in its outskirts. FLAMES-GIRAFFE spectra of about 400 red giants around (l,b)=(0°,-10°)
• Detailed abundances for M giants in two inner bulge fields from Infrared Spectroscopy
• Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy
• Deep SDSS optical spectroscopy of distant halo stars I. Atmospheric parameters and stellar metallicity distribution
• Metallicity Distribution Functions, Radial Velocities, and Alpha Element Abundances in Three Off-Axis Bulge Fields
• APOGEE Kinematics I: Overview of the Kinematics of the Galactic Bulge as Mapped by APOGEE
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• Chemodynamical Modelling of the Galactic Bulge and Bar
• The Giraffe Inner Bulge Survey (GIBS) II. Metallicity distributions and alpha element abundances at fixed Galactic latitude
• The origin of pseudobulges in cosmological simulations of galaxy formation
• Mapping a stellar disk into a boxy bulge: The outside-in part of the Milky Way bulge formation
• Young stars in an old bulge: a natural outcome of internal evolution in the Milky Way
• Metallicity gradients through disk Instability: A simple model for the Milky Way's boxy bulge
• A two-phase scenario for bulge assembly in LCDM cosmologies
• Natures of a clump-origin bulge: a pseudobulge-like but old metal-rich bulge
• Very Metal-poor Stars in the Outer Galactic Bulge Found by the Apogee Survey
• Accelerated post-AGB evolution, initial-final mass relations, and the star-formation history of the Galactic bulge
• Is there a metallicity ceiling to form carbon stars? - A novel technique reveals a scarcity of C stars in the inner M31 disk
• N-body simulation insights into the X-shaped bulge of the Milky Way: Kinematics and distance to the Galactic Centre
• Metallicity and kinematics of the bar in-situ
• Baade's window with APOGEE: Metallicities, ages and chemical abundances
• Chemical abundances in Galactic planetary nebulae with Spitzer spectra
• Kinematics in the Galactic Bulge with APOGEE: II. High-Order Kinematical Moments and Comparison to Extragalactic Bar Diagnostics
• Cosmic variance in [O/Fe] in the Galactic disk
• Evidence for a metal-poor population in the inner Galactic Bulge
• The case for high precision in elemental abundances of stars in the era of large spectroscopic surveys
• Low-mass lithium-rich AGB stars in the Galactic bulge: evidence for Cool Bottom Processing?

Cited by in corpus (37)

• The Close Binary Fraction of Solar-type Stars is Strongly Anti-correlated with Metallicity
• Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
• Estimating stellar birth radii and the time evolution of the Milky Way's ISM metallicity gradient
• The Poor Old Heart of the Milky Way
• The Milky Way bar and bulge revealed by APOGEE DR16 and Gaia EDR3
• Predicting the binary black hole population of the Milky Way with cosmological simulations
• The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
• How Many Components? Quantifying the Complexity of the Metallicity Distribution in the Milky Way Bulge with APOGEE
• High Eccentricities and High Masses Characterize Gravitational-wave Captures in Galactic Nuclei as Seen by Earth-based Detectors
• APOGEE DR14/DR15 Abundances in the Inner Milky Way
• The Pristine Inner Galaxy Survey (PIGS) II: Uncovering the most metal-poor populations in the inner Milky Way
• The inner two degrees of the Milky Way. Evidence of a chemical difference between the Galactic Center and the surrounding inner bulge stellar populations
• Super-Solar Metallicity Stars in the Galactic Center Nuclear Star Cluster: Unusual Sc, V, and Y Abundances
• The bimodal [Mg/Fe] versus [Fe/H] bulge sequence as revealed by APOGEE DR14
• Exploring the stellar age distribution of the Milky Way Bulge using APOGEE
• Star formation history and metallicity in the Galactic inner bulge revealed by the red giant branch bump
• The COMBS Survey -- II. Distinguishing the Metal-Poor Bulge from the Halo Interlopers
• The Star Formation History of the Milky Way's Nuclear Star Cluster
• The Three-Phase Evolution of the Milky Way
• Abundances of disk and Bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni
• CAPOS: The bulge Cluster APOgee Survey I. Overview and initial ASPCAP results
• The Milky Way's bulge star formation history as constrained from its bimodal chemical abundance distribution
• Blanco DECam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results
• Mapping the Interstellar Reddening and Extinction towards Baade's Window Using Minimum Light Colors of ab-type RR Lyrae Stars. Revelations from the De-reddened Color-Magnitude Diagrams
• Detailed chemical composition and orbit of the new globular cluster FSR1758: Implications for the accretion of the Sequoia dwarf galaxy onto the Milky Way
• NGC 6791: a probable bulge cluster without multiple populations
• Maximum Entropy Estimation of the Galactic Bulge Morphology via the VVV Red Clump
• Chemical Characterization of the Inner Galactic bulge:North-South Symmetry
• HERBS I: Metallicity and alpha enhancement along the Galactic bulge minor axis
• The chemical properties of the Milky Way's on-bar and off-bar regions: evidence for inhomogeneous star formation history in the bulge
• Searching for a kinematic signature of the moderately metal-poor stars in the Milky Way bulge using N-body simulations
• Radial velocities in the outermost disk toward the anticenter
• CO line observations of OH/IR stars in the inner Galactic Bulge: Characteristics of stars at the tip of the AGB
• Understanding the velocity distribution of the Galactic Bulge with APOGEE and Gaia
• The multi-zone chemical evolution of the Galactic bulge: predicting abundances for different radial zones
• The Spheroidal Bulge of the Milky Way: Chemodynamically Distinct from the Inner-Thick Disc and Bar
• The COMBS Survey -- III. The Chemodynamical Origins of Metal-Poor Bulge Stars