The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud

Abstract

The Milky Way (MW) offers a uniquely detailed view of galactic structure and is often regarded as a prototypical spiral galaxy. But recent observations indicate that the MW is atypical: it has an undersized supermassive black hole at its centre; it is surrounded by a very low mass, excessively metal-poor stellar halo; and it has an unusually large nearby satellite galaxy, the Large Magellanic Cloud (LMC). Here we show that the LMC is on a collision course with the MW with which it will merge in $2.4_{-0.8}^{+1.2}$ Gyrs (68% confidence level). This catastrophic and long-overdue event will restore the MW to normality. Using the EAGLE galaxy formation simulation, we show that, as a result of the merger, the central supermassive black hole will increase in mass by up to a factor of 8. The Galactic stellar halo will undergo an equally impressive transformation, becoming 5 times more massive. The additional stars will come predominantly from the disrupted LMC, but a sizeable number will be ejected onto the halo from the stellar disc. The post-merger stellar halo will have the median metallicity of the LMC, [Fe/H]=-0.5 dex, which is typical of other galaxies of similar mass to the MW. At the end of this exceptional event, the MW will become a true benchmark for spiral galaxies, at least temporarily.

arXiv comment12 pages, 8 figures, the published version in MNRAS

References in corpus (90)

• A Universal Density Profile from Hierarchical Clustering
• The Structure of Cold Dark Matter Halos
• The Demography of Massive Dark Objects in Galaxy Centres
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The observed properties of dwarf galaxies in and around the Local Group
• Planck 2013 results. I. Overview of products and scientific results
• Gasdynamics and Starbursts in Major Mergers
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The mass distribution and gravitational potential of the Milky Way
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Co-formation of the Galactic disc and the stellar halo
• The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy Formation
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• Active Galactic Nuclei: what's in a name?
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Black Holes in Galaxy Mergers: Evolution of Quasars
• New Understanding of Large Magellanic Cloud Structure, Dynamics and Orbit from Carbon Star Kinematics
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• Galactic stellar haloes in the CDM model
• Direct cosmological simulations of the growth of black holes and galaxies
• The EAGLE simulations of galaxy formation: public release of halo and galaxy catalogues
• Third-Epoch Magellanic Cloud Proper Motions I: HST/WFC3 data and Orbit Implications
• The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars
• The Star Formation History of the Large Magellanic Cloud
• Evolution of galaxy stellar masses and star formation rates in the EAGLE simulations
• In disguise or out of reach: first clues about in-situ and accreted stars in the stellar halo of the Milky Way from Gaia DR2
• The Dual Origin of Stellar Halos
• The dark nemesis of galaxy formation: why hot haloes trigger black hole growth and bring star formation to an end
• Cosmological simulations of the formation of the stellar haloes around disc galaxies
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Black Holes on FIRE: Stellar Feedback Limits Early Feeding of Galactic Nuclei
• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• Colours and luminosities of z=0.1 simulated galaxies in the EAGLE simulations
• Black hole evolution: I. Supernova-regulated black hole growth
• A timing constraint on the (total) mass of the Large Magellanic Cloud
• The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey
• A chronicle of galaxy mass assembly in the EAGLE simulation
• Broken and unbroken: the Milky Way and M31 stellar haloes
• The Auriga Stellar Haloes: Connecting stellar population properties with accretion and merging history
• Contributions to the accreted stellar halo: an atlas of stellar deposition
• Building Late-Type Spiral Galaxies by In-Situ and Ex-Situ Star Formation
• 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 mass of the Milky Way from satellite dynamics
• A Magellanic Origin of the DES Dwarfs
• Dark matter haloes determine the masses of supermassive black holes
• Inferring the Andromeda Galaxy's mass from its giant southern stream with Bayesian simulation sampling
• Formation of In Situ Stellar Haloes in Milky Way-Mass Galaxies
• The Missing Satellites of the Magellanic Clouds? Gaia Proper Motions of the Recently Discovered Ultra-Faint Galaxies
• Satellite abundances around bright isolated galaxies
• Stellar haloes of simulated Milky Way-like galaxies: Chemical and kinematic properties
• Gamma-Ray Bursts and the Earth: Exploration of Atmospheric, Biological, Climatic and Biogeochemical Effects
• The Dragonfly Nearby Galaxies Survey. I. Substantial variation in the diffuse stellar halos around spiral galaxies
• The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor
• Diverse Stellar Haloes in Nearby Milky Way-Mass Disc Galaxies
• How Common are the Magellanic Clouds?
• Supermassive black holes and their host spheroids II. The red and blue sequence in the $M_{\mathrm{BH}}-M_{\ast ,\mathrm{sph}}$ diagram
• Orbits of Massive Satellite Galaxies: I. A Close Look at the Large Magellanic Cloud and a New Orbital History for M33
• Supermassive black holes in the EAGLE Universe. Revealing the observables of their growth
• The radial profile and flattening of the Milky Way's stellar halo to $80$kpc from the SEGUE K-giant Survey
• Satellites of LMC-Mass Dwarfs: Close Friendships Ruined by Milky Way Mass Halos
• The M31 Velocity Vector. III. Future Milky Way-M31-M33 Orbital Evolution, Merging, and Fate of the Sun
• The GHOSTS survey. II. The diversity of Halo Color and Metallicity Profiles of Massive Disk Galaxies
• The Eating Habits of Milky Way Mass Halos: Destroyed Dwarf Satellites and the Metallicity Distribution of Accreted Stars
• Investigating the Andromeda Stream: II. Orbital Fits and Properties of the Progenitor
• The Collision Between The Milky Way And Andromeda
• Warps and waves in the stellar discs of the Auriga cosmological simulations
• The Copernicus Complexio: a high-resolution view of the small-scale Universe
• The link between galaxy and black hole growth in the EAGLE simulation
• Identifying true satellites of the Magellanic Clouds
• The masses and metallicities of stellar haloes reflect galactic merger histories
• A fully cosmological model of a Monoceros-like ring
• Global Properties of M31's Stellar Halo from the SPLASH Survey: II. Metallicity Profile
• The rapid growth phase of supermassive black holes
• The slight spin of the old stellar halo
• Bulge Formation via Mergers in Cosmological Simulations
• Substructure in the stellar halos of the Aquarius simulations
• Stellar Halo Constraints on Simulated Late Type Galaxies
• Galaxy And Mass Assembly (GAMA): In Search of Milky-Way Magellanic Cloud Analogues
• Towards an understanding of the evolution of the scaling relations for supermassive black holes
• Galaxies grow their bulges and black holes in diverse ways
• The Satellite Luminosity Functions of Galaxies in SDSS
• On the stellar halo metallicity profile of Milky Way-like galaxies in the Auriga simulations
• Space Motions of the Dwarf Spheroidal Galaxies Draco and Sculptor based on HST Proper Motions with ~10-year Time Baseline
• Evolution of LMC/M33-mass dwarf galaxies in the EAGLE simulation
• The accreted stellar halo as a window on halo assembly in L* galaxies

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• The Milky Way total mass profile as inferred from Gaia DR2
• Milky Way Satellite Census. II. Galaxy--Halo Connection Constraints Including the Impact of the Large Magellanic Cloud
• Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud
• The total stellar halo mass of the Milky Way
• The mass of our Milky Way
• Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by $S^5$
• The Chemo-Dynamical Groups of Galactic Globular Clusters
• Galactic Archaeology with Gaia
• The effect of the LMC on the Milky Way system
• The merger and assembly histories of Milky Way- and M31-like galaxies with TNG50: disk survival through mergers
• Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations
• Evolution of galactic planes of satellites in the EAGLE simulation
• The SAGA Survey. III. A Census of 101 Satellite Systems around Milky Way-mass Galaxies
• Milky Way total Mass derived by Rotation Curve and Globular Cluster kinematics from Gaia EDR3
• The Saga of M81: Global View of a Massive Stellar Halo in Formation
• The Magellanic System: the puzzle of the leading gas stream
• A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS and SDSS
• A SkyMapper view of the Large Magellanic Cloud: The dynamics of stellar populations
• How Unusual is the Milky Way's Assembly History?
• The VMC survey -- XXXVIII. Proper motion of the Magellanic Bridge
• The twisted dark matter halo of the Milky Way
• The SAGA Survey. IV. The Star Formation Properties of 101 Satellite Systems around Milky Way-mass Galaxies
• The QuaStar Survey: Detecting Hidden Low-Velocity Gas in the Milky Way's Circumgalactic Medium
• Radiative Turbulent Mixing Layers and the Survival of Magellanic Debris
• On the Mass Assembly History of the Local Group
• Apocalypse When? No Certainty of a Milky Way -- Andromeda Collision
• Determining Satellite Infall Times Using Machine Learning
• Discovery of a Rare Group of Dwarf Galaxies in the Local Universe
• The VMC survey -- LIV. The internal kinematics of the LMC with new VISTA observations