Gaia EDR3 proper motions of Milky Way dwarfs I: 3D Motions and Orbits

Abstract

Based on Gaia Early Data Release 3 (EDR3), we estimate the proper motions for 46 dwarf spheroidal galaxies (dSphs) of the Milky Way. The uncertainties in proper motions, determined by combining both statistical and systematic errors, are smaller by a factor 2.5, when compared with Gaia Data Release 2. We have derived orbits in four Milky Way potential models that are consistent with the MW rotation curve, with total mass ranging from $2.8\times 10^{11}$ $M_{\odot }$ to $15\times 10^{11}$ $M_{\odot }$. Although the type of orbit (ellipse or hyperbola) are very dependent on the potential model, the pericenter values are firmly determined, largely independent of the adopted MW mass model. By analyzing the orbital phases, we found that the dSphs are highly concentrated close to their pericenter, rather than to their apocenter as expected from Kepler's law. This may challenge the fact that most dSphs are Milky Way satellites, or alternatively indicates an unexpected large number of undiscovered dSphs lying very close to their apocenters. Between half and two thirds of the satellites have orbital poles that indicate them to orbit along the Vast Polar Structure (VPOS), with the vast majority of these co-orbiting in a common direction also shared by the Magellanic Clouds, which is indicative of a real structure of dSphs.

3rd version: 26 pages, 5 Figures, 6 Tables, version consistent with that to be published in the Astrophysical Journal

References in corpus (33)

• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• Gaia Early Data Release 3: The astrometric solution
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• The Milky Way total mass profile as inferred from Gaia DR2
• The DART imaging and CaT survey of the Fornax Dwarf Spheroidal Galaxy
• Stellar Velocities in the Carina, Fornax, Sculptor and Sextans dSph Galaxies: Data from the Magellan/MMFS Survey
• The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?
• Exploring Halo Substructure with Giant Stars XI: The Tidal Tails of the Carina Dwarf Spheroidal and the Discovery of Magellanic Cloud Stars in the Carina Foreground
• The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
• Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1
• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• Farthest Neighbor: The Distant Milky Way Satellite Eridanus II
• Exploring Halo Substructure with Giant Stars X. Extended Dark Matter or Tidal Disruption?: The Case for the Leo I Dwarf Spheroidal Galaxy
• Analytical properties of Einasto dark matter haloes
• The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids
• Stellar kinematics in the remote Leo II dwarf spheroidal galaxy -- Another brick in the wall
• M31 Transverse Velocity and Local Group Mass from Satellite Kinematics
• A spectroscopic confirmation of the Bootes II dwarf spheroidal
• The Milky Way's Disk of Classical Satellite Galaxies in Light of Gaia DR2
• Bayesian analysis of resolved stellar spectra: application to MMT/Hectochelle Observations of the Draco dwarf spheroidal
• Birds of a Feather? Magellan/IMACS Spectroscopy of the Ultra-Faint Satellites Grus II, Tucana IV, and Tucana V
• Leo V: Spectroscopy of a Distant and Disturbed Satellite
• A Milky Way with a massive, centrally concentrated thick disc: new Galactic mass models for orbit computations
• Prolate rotation and metallicity gradient in the transforming dwarf galaxy Phoenix
• Multiple Chemodynamic Stellar Populations of the Ursa Minor Dwarf Spheroidal Galaxy
• Toward a Complete Understanding of the Magellanic Stream Formation
• A robust estimate of the Milky Way mass from rotation curve data
• The Vast Polar Structure of the Milky Way Attains New Members
• A multi-epoch kinematic study of the remote dwarf spheroidal galaxy Leo II
• Orbital evidences for dark-matter-free Milky Way dwarf spheroidal galaxies
• Proper Motion of the Leo II Dwarf Galaxy Based On Hubble Space Telescope Imaging
• BALRoGO: Bayesian Astrometric Likelihood Recovery of Galactic Objects -- Global properties of over one hundred globular clusters with Gaia EDR3

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• Structure and kinematics of tidally limited satellite galaxies in LCDM
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• Sizing from the Smallest Scales: The Mass of the Milky Way
• Tidally induced velocity gradients in the Milky Way dwarf spheroidal satellites
• Gaia-ESO Survey: Detailed elemental abundances in red giants of the peculiar globular cluster NGC 1851
• Constraining density and metallicity of the Milky Way's hot gas halo from O VII spectra and ram-pressure stripping
• Exploring the effects of primordial non-Gaussianity at galactic scales
• HubPUG: Proper Motions for Local Group Dwarfs observed with HST utilizing Gaia as a Reference Frame
• A New Proper Motion Determination of Leo I
• Eridanus IV: an Ultra-Faint Dwarf Galaxy Candidate Discovered in the DECam Local Volume Exploration Survey
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