Galaxies lacking dark matter produced by close encounters in a cosmological simulation

Abstract

The standard cold dark matter plus cosmological constant model predicts that galaxies form within dark-matter haloes, and that low-mass galaxies are more dark-matter dominated than massive ones. The unexpected discovery of two low-mass galaxies lacking dark matter immediately provoked concerns about the standard cosmology and ignited explorations of alternatives, including self-interacting dark matter and modified gravity. Apprehension grew after several cosmological simulations using the conventional model failed to form adequate numerical analogues with comparable internal characteristics (stellar masses, sizes, velocity dispersions and morphologies). Here we show that the standard paradigm naturally produces galaxies lacking dark matter with internal characteristics in agreement with observations. Using a state-of-the-art cosmological simulation and a meticulous galaxy-identification technique, we find that extreme close encounters with massive neighbours can be responsible for this. We predict that approximately 30 percent of massive central galaxies (with at least 1e11 solar masses in stars) harbour at least one dark-matter-deficient satellite (with 1e8 - 1e9 solar masses in stars). This distinctive class of galaxies provides an additional layer in our understanding of the role of interactions in shaping galactic properties. Future observations surveying galaxies in the aforementioned regime will provide a crucial test of this scenario.

55 pages, 4 figures, 13 supplementary figures. 29 pages, 4 figures. Accepted for publication in Nature Astronomy. To appear on 14-February-2022. Published version: https://www.nature.com/articles/s41550-021-01598-4

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• X-rays from solar system objects
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• The ultra-diffuse galaxy NGC 1052-DF2 with MUSE: II. The population of DF2: stars, clusters and planetary nebulae
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Cited by in corpus (9)

• A trail of dark matter-free galaxies from a bullet dwarf collision
• The stellar populations of quiescent ultra-diffuse galaxies from optical to mid-infrared spectral energy distribution fitting
• The Three Hundred project: connection between star formation quenching and dynamical evolution in and around simulated galaxy clusters
• Ultra-deep imaging of NGC1052-DF2 and NGC1052-DF4 to unravel their origins
• The large-scale structure of globular clusters in the NGC 1052 group
• Testing the galaxy collision induced formation scenario for the trail of dark matter deficient galaxies with the susceptibility of globular clusters to the tidal force
• A candidate dark matter deficient dwarf galaxy in the Fornax cluster identified through overluminous star clusters
• A detailed star formation history for the extremely diffuse Andromeda XIX dwarf galaxy
• An effective model for the tidal disruption of satellites undergoing minor mergers with axisymmetric primaries