Are disks of satellites comprised of tidal dwarf galaxies?

Abstract

It was found that satellites of nearby galaxies can form flattened co-rotating structures called disks of satellites or planes of satellites. Their existence is not expected by the current galaxy formation simulations in the standard dark-matter-based cosmology. On the contrary, modified gravity offers a promising alternative: the objects in the disks of satellites are tidal dwarf galaxies, that is small galaxies that form from tidal tails of interacting galaxies. After introducing the topic, we review here our work on simulating the formation of the disks of satellites of the Milky Way and Andromeda galaxies. The initial conditions of the simulation were tuned to reproduce the observed positions, velocities and disk orientations of the galaxies. The simulation showed that the galaxies had a close flyby 6.8Gyr ago. One of the tidal tails produced by the Milky Way was captured by Andromeda. It formed a cloud of particles resembling the disk of satellites at Andromeda by its size, orientation, rotation and mass. A hint of a disk of satellites was formed at the Milky Way too. In addition, the encounter induced a warp in the disk of the simulated Milky Way that resembles the real warp by its magnitude and orientation. We present here, for the first time, the proper motions of the members of the disk of satellites of Andromeda predicted by our simulation. Finally, we point out some of the remaining open questions which this hypothesis for the formation of disks of satellites brings up.

16 pages, 4 figures. Accepted as an invited contribution to the special issue "Challenges in Our Understanding of Dwarf Galaxies" of the Galaxies journal. Shortened and updated version of the paper Bilek et al., A&A, 614, A59, 2018

References in corpus (31)

• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• The Atlas3D project -- XXIX. The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• Clumpy Galaxies in GOODS and GEMS: Massive Analogs of Local Dwarf Irregulars
• Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation
• The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites
• Infall of substructures onto a Milky Way-like dark halo
• Two Planes of Satellites in the Centaurus A Group
• The Milky Way's Disk of Classical Satellite Galaxies in Light of Gaia DR2
• The KBC void and Hubble tension contradict $\Lambda$CDM on a Gpc scale $-$ Milgromian dynamics as a possible solution
• Velocity anti-correlation of diametrically opposed galaxy satellites in the low redshift universe
• A massive blow for $\Lambda$CDM $-$ the high redshift, mass, and collision velocity of the interacting galaxy cluster El Gordo contradicts concordance cosmology
• Dynamical friction in modified Newtonian dynamics
• On the stellar masses of giant clumps in distant star-forming galaxies
• Star formation triggered by galaxy interactions in modified gravity
• Testing MOND Over a Wide Acceleration Range in X-Ray Ellipticals
• Comparing the observable properties of dwarf galaxies on and off the Andromeda plane
• RAyMOND: An N-body and hydrodynamics code for MOND
• Theia: Faint objects in motion or the new astrometry frontier
• Newly discovered dwarf galaxies in the MATLAS low density fields
• MOND rotation curves of very low mass spiral galaxies
• The proper motion of Andromeda from Gaia eDR3: confirming a nearly radial orbit
• The mass-metallicity relation of tidal dwarf galaxies
• Understanding the internal dynamics of elliptical galaxies without non-baryonic dark matter
• Local Group galaxies emerge from the dark
• Long Tidal Tails in Merging Galaxies and Their Implications
• Spiral arms and disc stability in the Andromeda galaxy
• On the absence of backsplash analogues to NGC 3109 in the $\Lambda$CDM framework
• Evolution of globular-cluster systems of ultra-diffuse galaxies due to dynamical friction in MOND gravity