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

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Cautun , M , Deason , A J , Frenk , C S & McAlpine , S 2019 , ' The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud ' , Monthly Notices of the Royal Astronomical Society , vol. 483 , no. 2 , pp. 2185-2196 . https://doi.org/10.1093/mnras/sty3084

Title: The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud
Author: Cautun, Marius; Deason, Alis J.; Frenk, Carlos S.; McAlpine, Stuart
Contributor: University of Helsinki, Department of Physics
Date: 2019-02
Language: eng
Number of pages: 12
Belongs to series: Monthly Notices of the Royal Astronomical Society
ISSN: 0035-8711
URI: http://hdl.handle.net/10138/308464
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) Gyr (68 per cent 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 on to 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.
Subject: Galaxy: halo
galaxies: dwarfs
galaxies: haloes
galaxies: kinematics and dynamics
Magellanic Clouds
SUPERMASSIVE BLACK-HOLES
ACCRETED STELLAR HALO
WAY-LIKE GALAXIES
MILKY-WAY
STAR-FORMATION
COSMOLOGICAL SIMULATIONS
EAGLE SIMULATIONS
ANDROMEDA GALAXY
MASS
EVOLUTION
115 Astronomy, Space science
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