An intriguing coincidence between the majority of vast polar structure dwarfs and a recent major merger at the M31 position

Abstract

A significant part of the Milky Way (MW) dwarf galaxies orbit within a Vast POlar Structure (VPOS), which is perpendicular to the Galactic disc and whose origin has not yet been identified. It includes the Large Magellanic Cloud (LMC) and its six dynamically associated dwarf galaxies. Andromeda Galaxy (M31) experienced a major merger two to three billion years ago, and its accurate modelling predicts that an associated tidal tail is pointing towards the Galaxy. Here, we tested a possible association between M31 tidal tail particles and MW dwarf galaxies, focusing first on the LMC and its associated dwarfs since they are less affected by ram pressure. We traced back these dwarf galaxy orbits by one billion years and calculated their association with the tidal tail particles in the 6D phase space, based on their proper motion from \textit{Gaia} DR3. We find that for low-mass MW models (total mass less than 5 $\times 10^{11}{M}_{\odot }$), the separation in the 6D space can be less than 1$\sigma$ for most of the M31 modelling, albeit with a significant degree of freedom due to the still unknown proper motion of M31. We further discover that many other dwarfs could also be associated with the M31 tidal tails if their motions had been radially slowed, as expected from the ram pressure exerted by the MW corona. This intriguing coincidence could explain the origin of the VPOS, which resulted from a matter exchange between M31 and MW.

arXiv commentA&A, accepted 20th December 2024, published online 04 February 2025, 10 pages, 9 figures, and Appendix A, B, C, D & E

References in corpus (43)

• A Universal Density Profile from Hierarchical Clustering
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• galpy: A Python Library for Galactic Dynamics
• Gaia Early Data Release 3: The astrometric solution
• A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy
• Third-Epoch Magellanic Cloud Proper Motions I: HST/WFC3 data and Orbit Implications
• The Circular Velocity Curve of the Milky Way from $5$ to $25$ kpc
• Third-Epoch Magellanic Cloud Proper Motions II: The Large Magellanic Cloud Rotation Field in Three Dimensions
• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall
• Dwarf Galaxy Planes: the discovery of symmetric structures in the Local Group
• The Detailed Star Formation History in the Spheroid, Outer Disk, and Tidal Stream of the Andromeda Galaxy
• The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites
• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• From Tidal Dwarf Galaxies to Satellite Galaxies
• On the estimation of the Local Dark Matter Density using the rotation curve of the Milky Way
• A 2-3 billion year old major merger paradigm for the Andromeda galaxy and its outskirts
• Do dwarf galaxies form in tidal tails?
• Analytical properties of Einasto dark matter haloes
• The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor
• The vast thin plane of M31 co-rotating dwarfs: an additional fossil signature of the M31 merger and of its considerable impact in the whole Local Group
• A dynamical model of the local cosmic expansion
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• The Milky Way's Disk of Classical Satellite Galaxies in Light of Gaia DR2
• Limit on the LMC mass from a census of its satellites
• First Gaia Dynamics of the Andromeda System: DR2 Proper Motions, Orbits, and Rotation of M31 and M33
• Detection of the Keplerian decline in the Milky Way rotation curve
• Detection of the LMC-induced sloshing of the Galactic halo
• The Magellanic Stream System: I. Ram-pressure tails and the relics of the collision between the Magellanic Clouds
• Tidal dwarf galaxies in the nearby Universe
• Making Counter-Orbiting Tidal Debris: The Origin of the Milky Way Disc of Satellites
• A Milky Way with a massive, centrally concentrated thick disc: new Galactic mass models for orbit computations
• Does the dwarf galaxy system of the Milky Way originate from Andromeda?
• Toward a Complete Understanding of the Magellanic Stream Formation
• Galaxies lacking dark matter in the Illustris simulation
• Which Milky Way masses are consistent with the slightly declining 5-25 kpc rotation curve?
• A portrait of the Vast Polar Structure as a young phenomenon: hints from its member satellites
• The accretion history of the Milky Way. I. How it shapes globular clusters and dwarf galaxies
• The survey of planetary nebulae in Andromeda (M31) VI. Kinematics of M31 inner-halo substructures and comparison with major-merger simulation predictions
• Lessons from the Magellanic System and its modeling
• Reassessing the proper motions of M31/M33 with Gaia DR3. Unraveling systematic uncertainties
• Dark matter fraction derived from the M31 rotation curve
• The Milky Way accretion history compared to cosmological simulations -- from bulge to dwarf galaxy infall

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