VLT Spectroscopy of Ultra-Faint Dwarf Galaxies. 1. Boötes I, Leo IV, Leo V

Abstract

We perform consistent reductions and measurements for three ultra-faint dwarf galaxies (UFDs): Boötes I, Leo IV and Leo V. Using the public archival data from the GIRAFFE spectrograph on the Very Large Telescope (VLT), we locate new members and provide refined measurements of physical parameters for these dwarf galaxies. We identify nine new Leo IV members and four new Leo V members, and perform a comparative analysis of previously discovered members. Additionally, we identify one new binary star in both Leo IV and Leo V. After removing binary stars, we recalculate the velocity dispersions of Boötes I and Leo IV to be 5.1${}_{-0.8}^{+0.7}$ and 3.4${}_{-0.9}^{+1.3}$ km s${}^{-1}$, respectively; We do not resolve the Leo V velocity dispersion. We identify a weak velocity gradient in Leo V that is $\sim$4$\times$ smaller than the previously calculated gradient and that has a corresponding position angle which differs from the literature value by $\sim$120 deg. Combining the VLT data with previous literature, we re-analyze the Boötes I metallicity distribution function and find that a model including infall of pristine gas while Boötes I was forming stars best fits the data. Our analysis of Leo IV, Leo V and other UFDs will enhance our understanding of these enigmatic stellar populations and contribute to future dark matter studies. This is the first in a series of papers examining thirteen UDFs observed with VLT/GIRAFFE between 2009 and 2017. Similar analyses of the remaining ten UFDs will be presented in forthcoming papers.

arXiv comment29 pages, 18 figures, 8 tables. Accepted for publication on ApJ. Code and data can be found at https://github.com/sazabi4/vlt_dwarf/

References in corpus (69)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• emcee: The MCMC Hammer
• The Gaia mission
• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• Overview of the DESI Legacy Imaging Surveys
• The Dartmouth Stellar Evolution Database
• Multimodal nested sampling: an efficient and robust alternative to MCMC methods for astronomical data analysis
• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• Cats and Dogs, Hair and A Hero: A Quintet of New Milky Way Companions
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• Accurate masses for dispersion-supported galaxies
• Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data
• The Faintest Dwarf Galaxies
• Beasts of the Southern Wild: Discovery of nine Ultra Faint satellites in the vicinity of the Magellanic Clouds
• The Observed properties of Dark Matter on small spatial scales
• A Faint New Milky Way Satellite in Bootes
• An extensive library of 2500-10500 Ang synthetic spectra
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
• Milky Way Satellite Census. III. Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies
• Galactic Globular Cluster Metallicity Scale from the Calcium Triplet. II. Rankings, Comparisons and Puzzles
• A Keck/DEIMOS spectroscopic survey of faint Galactic satellites: searching for the least massive dwarf galaxies
• A Complete Spectroscopic Survey of the Milky Way Satellite Segue 1: The Darkest Galaxy
• Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall
• Internal Kinematics of the Fornax Dwarf Spheroidal Galaxy
• The Least Luminous Galaxy: Spectroscopy of the Milky Way Satellite Segue 1
• Accurate Stellar Kinematics at Faint Magnitudes: application to the Bootes~I dwarf spheroidal galaxy
• A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
• Chemical Enrichment in the Faintest Galaxies: the Carbon and Iron Abundance Spreads in the Boötes I Dwarf Spheroidal Galaxy and the Segue 1 System
• Leo V: A Companion of a Companion of the Milky Way Galaxy
• Stellar Kinematics and Metallicities in the Ultra-Faint Dwarf Galaxy Reticulum II
• Farthest Neighbor: The Distant Milky Way Satellite Eridanus II
• Study of the Sextans dwarf spheroidal galaxy from the DART CaII triplet survey
• Constraining the WDM Particle Mass with Milky Way Satellites
• Kinematics and chemistry of recently discovered Reticulum 2 and Horologium 1 dwarf galaxies
• Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes
• Ultra-Light Dark Matter in Ultra-Faint Dwarf Galaxies
• The Southern Stellar Stream Spectroscopic Survey ($S^5$): Overview, Target Selection, Data Reduction, Validation, and Early Science
• Magellan/M2FS Spectroscopy of Tucana 2 and Grus 1
• The Near Infrared Ca II Triplet as Metallicity Indicator: II Extension to extremely metal-poor metallicity regimes
• Snake in the Clouds: A new nearby dwarf galaxy in the Magellanic bridge
• The [Fe/H], [C/Fe], and [alpha/Fe] distributions of the Bootes I Dwarf Spheroidal Galaxy
• Tidal Signatures in the Faintest Milky Way Satellites: The Detailed Properties of Leo V, Pisces II and Canes Venatici II
• Variable stars in the newly discovered Milky Way satellite in Bootes
• A Complete Spectroscopic Survey of the Milky Way satellite Segue 1: Dark matter content, stellar membership and binary properties from a Bayesian analysis
• A Global Analysis of Dark Matter Signals from 27 Dwarf Spheroidal Galaxies using 11 Years of Fermi-LAT Observations
• Two Ultra-Faint Milky Way Stellar Systems Discovered in Early Data from the DECam Local Volume Exploration Survey
• An extended halo around an ancient dwarf galaxy
• Magellan/M2FS Spectroscopy of the Reticulum 2 Dwarf Spheroidal Galaxy
• The Leo IV dwarf spheroidal galaxy: color-magnitude diagram and pulsating stars
• The chemical evolution of the Bootes I ultra-faint dwarf galaxy
• Leo V: Spectroscopy of a Distant and Disturbed Satellite
• Elemental Abundances in M31: The Kinematics and Chemical Evolution of Dwarf Spheroidal Satellite Galaxies
• Chemical Abundances of new member stars in the Tucana II dwarf galaxy
• Triangulum II: Possibly a Very Dense Ultra-Faint Dwarf Galaxy
• The enigmatic pair of dwarf galaxies Leo IV and Leo V: coincidence or common origin?
• Discovery of distant RR Lyrae stars in the Milky Way using DECam
• A Gaia DR 2 and VLT/FLAMES search for new satellites of the LMC
• Chemical evolution of ultra-faint dwarf galaxies in the self-consistently calculated IGIMF theory
• Dynamical evidence for a strong tidal interaction between the Milky Way and its satellite, Leo V
• Cleaning spectroscopic samples of stars in nearby dwarf galaxies: The use of the nIR MgI line to weed out Milky Way contaminants
• Indirect dark matter searches in the dwarf satellite galaxy Ursa Major II with the MAGIC Telescopes
• Serendipitous discovery of RR Lyrae stars in the Leo V ultra-faint galaxy
• Signatures of Tidal Disruption in Ultra-Faint Dwarf Galaxies: A Combined HST, Gaia, and MMT/Hectochelle Study of Leo V
• Leo IV & V - A possible dwarf galaxy pair ?
• $J$-factor estimation of Draco, Sculptor and Ursa Minor dwarf spheroidal galaxies with the member/foreground mixture model
• The MUSE-Faint survey: I. Spectroscopic evidence for a star cluster in Eridanus 2 and constraints on MACHOs as a constituent of dark matter

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