Most dwarf spheroidal galaxies surrounding the Milky Way cannot be dark-matter dominated satellites

Abstract

Milky Way dwarf spheroidal galaxies are the tiniest observed galaxies and are currently associated with the largest fractions of dark matter, which is revealed by their too large velocity dispersions. However, most of them are found near their orbital pericenters. This leads to a very low probability, P = 2 $10^{-7}$, that they could be long-lived satellites such as sub-halos predicted by cosmological simulations. Their proximity to their pericenters suggests instead that they are affected by tidal shocks, which provide sufficient kinematic energy to explain their high velocity dispersions. Dependency of the dark matter properties to their distance to the Milky Way appears to favor tidally shocked and out of equilibrium dSphs instead of self-equilibrium systems dominated by dark matter.

arXiv comment7 pages, 2 Figures, Printed at Proceedings of the 3rd World Summit on Exploring the Dark Side of the Universe (EDSU2020): March 9-13, 2020, Guadeloupe Islands, Eds. A. Novikov, P. Petroff and C. Royon, University of Kansas Libraries P229. An explanatory video based on hydrodynamical, N-body simulations optimizing the dynamics of stars can be found at: https://www.youtube.com/watch?v=m55iBXISYyE

References in corpus (14)

• galpy: A Python Library for Galactic Dynamics
• The mass distribution and gravitational potential of the Milky Way
• Clumps and streams in the local dark matter distribution
• Accurate masses for dispersion-supported galaxies
• A Universal Mass Profile for Dwarf Spheroidal Galaxies?
• The importance of tides for the Local Group dwarf spheroidals
• Gaia Proper Motions and Orbits of the Ultra-Faint Milky Way Satellites
• Rotation curve of the Milky Way from Classical Cepheids
• Star formation histories of dwarf galaxies in the FIRE simulations: dependence on mass and Local Group environment
• Internal kinematics and dynamical models of dwarf spheroidal galaxies around the Milky Way
• The effects of dynamical substructure on Milky Way mass estimates from the high velocity tail of the local stellar halo
• Sailing under the Magellanic Clouds: A DECam View of the Carina Dwarf
• On the absence of dark matter in dwarf galaxies surrounding the Milky Way
• The effect of tides on the Sculptor dwarf spheroidal galaxy