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SUMMARY:Galaxies lacking dark matter in the LCDM paradigm - Jorge Moreno (
 Pomona College)
DTSTART:20220624T103000Z
DTEND:20220624T113000Z
UID:TALK172277@talks.cam.ac.uk
CONTACT:Martin Haehnelt
DESCRIPTION: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 provok
 ed concerns about the standard cosmology and ignited explorations of alter
 natives\, including self-interacting dark matter and modified gravity. App
 rehension grew after several cosmological simulations using the convention
 al model failed to form adequate numerical analogues with comparable inter
 nal characteristics (stellar masses\, sizes\, velocity dispersions and mor
 phologies). Here we show that the standard paradigm naturally produces gal
 axies lacking dark matter with internal characteristics in agreement with 
 observations. Using a state-of-the-art cosmological simulation and a metic
 ulous galaxy-identification technique\, we find that extreme close encount
 ers with massive neighbours can be responsible for this. We predict that ~
 30% of massive central galaxies (with at least 1e11 solar masses in stars)
  harbour at least one dark-matter-deficient satellite (with 1e8–1e9 sola
 r masses in stars). This distinctive class of galaxies provides an additio
 nal layer in our understanding of the role of interactions in shaping gala
 ctic properties. Future observations surveying galaxies in the aforementio
 ned regime will provide a crucial test of this scenario.
LOCATION:in person &amp\; via zoom 
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