Metallicity Distribution Functions of Four Local Group dwarf galaxies

Abstract

We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 (WFC3) instrument aboard the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, 1) matching stars to isochrones in color-color diagrams, and 2) solving for the best linear combination of synthetic populations to match the observed color-color diagram. The synthetic technique reduces the effect of photometric scatter, and produces MDFs 30-50 % narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEM) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal rich cutoff and an extended metal poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition) and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies, therefore we also fit the `Best Accretion Model' of Lynden-Bell 1975. For Leo II, IC 1613 and Phoenix we find similar accretion parameters for the CEM, even though they all have different effective yields, masses, star formation histories and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution.

arXiv comment15 pages, 8 figures, accepted in AJ

References in corpus (68)

• On the variation of the Initial Mass Function
• Dwarf Galaxies of the Local Group
• The observed properties of dwarf galaxies in and around the Local Group
• The Dartmouth Stellar Evolution Database
• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• WFPC2 Stellar Photometry with HSTphot
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• Abundance Patterns in the Draco, Sextans and Ursa Minor Dwarf Spheroidal Galaxies
• VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: I. Nucleosynthesis and Abundance Ratios
• The Star Formation Histories of Local Group Dwarf Galaxies I. Hubble Space Telescope / Wide Field Planetary Camera 2 Observations
• The Progenitors of Dwarf Spheroidal Galaxies
• Simultaneous ram pressure and tidal stripping; how dwarf spheroidals lost their gas
• HI in Local Group Dwarf Galaxies and Stripping by the Galactic Halo
• On Extending the Mass-Metallicity Relation of Galaxies by 2.5 Decades in Stellar Mass
• The Tidal Evolution of Local Group Dwarf Spheroidals
• The Metamorphosis of Tidally Stirred Dwarf Galaxies
• Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
• The ACS Nearby Galaxy Survey Treasury VIII. The Global Star Formation Histories of 60 Dwarf Galaxies in the Local Volume
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
• The DART imaging and CaT survey of the Fornax Dwarf Spheroidal Galaxy
• VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: II. Implications for Understanding Galaxy Evolution
• Population Gradients in Local Group Dwarf Spheroidals
• A GALEX Ultraviolet Imaging Survey of Galaxies in the Local Volume
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• The Star Formation History of the Local Group dwarf galaxy Leo I
• Study of the Sextans dwarf spheroidal galaxy from the DART CaII triplet survey
• Early Gas Stripping as the Origin of the Darkest Galaxies in the Universe
• On the Efficiency of the Tidal Stirring Mechanism for the Origin of Dwarf Spheroidals: Dependence on the Orbital and Structural Parameters of the Progenitor Disky Dwarfs
• Non-parametric star formation histories for 5 dwarf spheroidal galaxies of the local group
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. IV. Alpha Element Distributions in Milky Way Dwarf Satellite Galaxies
• The Dearth of Neutral Hydrogen in Galactic Dwarf Spheroidal Galaxies
• Deep Hubble Space Telescope Imaging of IC 1613 II. The Star Formation History
• The Space Motion of Leo I: Hubble Space Telescope Proper Motion and Implied Orbit
• The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies
• Stellar kinematics in the remote Leo II dwarf spheroidal galaxy -- Another brick in the wall
• The extremely low-metallicity tail of the Sculptor dwarf spheroidal galaxy
• VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy
• On the extended structure of the Phoenix dwarf galaxy
• Star formation feedback and metal enrichment by SN Ia and SN II in dwarf spheroidal galaxies: the case of Draco
• Complexity on Small Scales II: Metallicities and Ages in the Leo II Dwarf Spheroidal Galaxy
• The ACS LCID project. X. The Star Formation History of IC 1613: Revisiting the Over-Cooling Problem
• The ACS LCID project. IX. Imprints of the early Universe in the radial variation of the star formation history of dwarf galaxies
• The MaGICC Baryon Cycle: The Enrichment History of Simulated Disc Galaxies
• The Chemical Evolution of Dwarf Spheroidal Galaxies: Dissecting the Inner Regions and their Stellar Populations
• Neutron-capture element deficiency of the Hercules dwarf spheroidal galaxy
• The stellar content of the Local Group dwarf galaxy Phoenix
• The metal-poor Knee in the Fornax Dwarf Spheroidal Galaxy
• The Aptly Named Phoenix Dwarf Galaxy
• How Typical Are The Local Group Dwarf Galaxies?
• The extensive age gradient of the Carina dwarf galaxy
• Chemical Abundances of the Leo II Dwarf Galaxy
• The metallicity distribution of the halo and the satellites of the Milky way in the hierarchical merging paradigm
• The Chemical Abundances of the Stellar Populations in the Leo I and Leo II dSph Galaxies
• Stellar Content and Recent Star Formation History of the Local Group Dwarf Irregular Galaxy IC1613
• The evolved stars of Leo II dSph galaxy from near-infrared UKIRT/WFCAM observations
• Stellar populations in the dwarf spheroidal galaxy Leo I
• New constraints on the chemical evolution of the dwarf spheroidal galaxy LeoI from VLT spectroscopy
• A first measurement of the Proper Motion of the Leo II dwarf spheroidal galaxy
• On the neutral gas distribution and kinematics in the dwarf irregular galaxy IC 1613
• A Wide-Field View of Leo II -- A Structural Analysis Using the SDSS
• Stellar Populations in the Phoenix Dwarf (dIrr/dSph) Galaxy as Observed by HST/WFPC2
• The shapes of Milky Way satellites: looking for signatures of tidal stirring
• Variable Stars in the Cetus dSph Galaxy: Population Gradients and Connections with the Star Formation History
• A wide-area view of the Phoenix dwarf galaxy from VLT/FORS imaging
• Wide-field Survey around Local Group Dwarf Spheroidal Galaxy Leo II: Spatial Distribution of Stellar Content
• The effect of gravitational tides on dwarf spheroidal galaxies
• The RR Lyrae Variable Population in the Phoenix Dwarf Galaxy
• A near-infrared study of AGB and red giant stars in the Leo I dSph galaxy

Cited by in corpus (11)

• The origin of accreted stellar halo populations in the Milky Way using APOGEE, $\text{Gaia}$, and the EAGLE simulations
• The statistical challenge of constraining the low-mass IMF in Local Group dwarf galaxies
• Observational properties of massive black hole binary progenitors
• Solo Dwarfs I: Survey introduction and first results for the Sagittarius Dwarf Irregular Galaxy
• Spectroscopic evolution of massive stars near the main sequence at low metallicity
• Metallicity Distribution Function of the Eridanus~II Ultra-Faint Dwarf Galaxy from Hubble Space Telescope Narrow-band Imaging
• From K giants to G dwarfs: stellar lifetime effects on metallicity distributions derived from red giants
• Metallicity distribution of the progenitor of the Giant Stellar Stream in the Andromeda Galaxy
• Chemical history of isolated dwarf galaxies of the Local Group: I. dSphs: Cetus and Tucana
• The Local Ultraviolet to Infrared Treasury I. Survey Overview of the Broadband Imaging
• A machine-learning photometric classifier for massive stars in nearby galaxies II. The catalog