Using dwarf satellite proper motions to determine their origin

Abstract

The highly organised distribution of satellite galaxies surrounding the Milky Way is a serious challenge to the concordance cosmological model. Perhaps the only remaining solution, in this framework, is that the dwarf satellite galaxies fall into the Milky Way's potential along one or two filaments, which may or may not plausibly reproduce the observed distribution. Here we test this scenario by making use of the proper motions of the Fornax, Sculptor, Ursa Minor and Carina dwarf spheroidals, and trace their orbits back through several variations of the Milky Way's potential and account for dynamical friction. The key parameters are the proper motions and total masses of the dwarf galaxies. Using a simple model we find no tenable set of parameters that can allow Fornax to be consistent with filamentary infall, mainly because the 1 sigma error on its proper motion is relatively small. The other three must walk a tightrope between requiring a small pericentre (less than 20 kpc) to lose enough orbital energy to dynamical friction and avoiding being tidally disrupted. We then employed a more realistic model with host halo mass accretion, and found that the four dwarf galaxies must have fallen in at least 5 Gyrs ago. This time interval is longer than organised distribution is expected to last before being erased by the randomisation of the satellite orbits.

9 pages, 5 figures, accepted for publication in MNRAS

References in corpus (18)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
• Forming Disk Galaxies in Lambda CDM Simulations
• Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies
• Is the SMC Bound to the LMC? The HST Proper Motion of the SMC
• A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies
• Galactic masers and the Milky Way circular velocity
• The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites
• Infall of substructures onto a Milky Way-like dark halo
• The Mass Profile of the Galaxy to 80 kpc
• Cosmic Ménage à Trois: The Origin of Satellite Galaxies On Extreme Orbits
• Tidal dwarf galaxies as a test of fundamental physics
• Satellites of Simulated Galaxies: survival, merging, and their relation to the dark and stellar halos
• Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV: Measurement for Sculptor
• Dwarf Spheroidals in MOND
• Satellite Systems around Galaxies in Hydrodynamic Simulations
• Gas depletion in Local Group dwarfs on ~250 kpc scales: Ram pressure stripping assisted by internal heating at early times
• MOND and the mass discrepancies in tidal dwarf galaxies

Cited by in corpus (33)

• Star formation sustained by gas accretion
• Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation
• Dwarf Galaxy Planes: the discovery of symmetric structures in the Local Group
• And yet it moves: The dangers of artificially fixing the Milky Way center of mass in the presence of a massive Large Magellanic Cloud
• The rotationally stabilized VPOS and predicted proper motions of the Milky Way satellite galaxies
• Co-orbiting satellite galaxy structures are still in conflict with the distribution of primordial dwarf galaxies
• The Three-Dimensional Structure of the M31 Satellite System; Strong Evidence for an Inhomogeneous Distribution of Satellites
• Infall Times for Milky Way Satellites From Their Present-Day Kinematics
• Dark matters on the scale of galaxies
• The failures of the standard model of cosmology require a new paradigm
• Can filamentary accretion explain the orbital poles of the Milky Way satellites?
• Does the dwarf galaxy system of the Milky Way originate from Andromeda?
• MOND vs. dark matter in light of historical parallels
• Galaxies lacking dark matter in the Illustris simulation
• 3D hydrodynamic simulations for the formation of the Local Group satellite planes
• On the Stability of Satellite Planes I: Effects of Mass, Velocity, Halo Shape and Alignment
• The Phantom of RAMSES user guide for galaxy simulations using Milgromian and Newtonian gravity
• N-body simulations of the Carina dSph in MOND
• Simulations of star forming main sequence galaxies in Milgromian gravity
• Hydrodynamical structure formation in Milgromian cosmology
• Dynamical History of the Local Group in $\Lambda$CDM
• A new line on the wide binary test of gravity
• The potential role of NGC 205 in generating Andromeda's vast thin co-rotating plane of satellite galaxies
• The Relevance of Dynamical Friction for the MW/LMC/SMC Triple System
• Directly testing gravity with Proxima Centauri
• Rotation curves of galaxies and the stellar mass-to-light ratio
• The Magellanic Clouds are very rare in the IllustrisTNG simulations
• Lessons from the Local Group (and beyond) on dark matter
• Galactic Orbits of Selected Companions of the Milky Way
• Survivors and Zombies: The Quenching and Disruption of Satellites around Milky Way Analogs
• Simulations of cluster ultra-diffuse galaxies in MOND
• Effect of the Solar dark matter wake on planets
• Fast particle-mesh code for Milgromian dynamics