Dark energy could influence individual galaxies
DOI: 10.1063/PT.5.028623
New Scientist : To account for the observation that the expansion of the universe is accelerating, cosmologists have evoked a mysterious force called dark energy. Dark energy’s influence is evident on cosmological scales, but could it also play out on galactic scales? Stephen Hsu of Michigan State University in East Lansing set out to answer that question—and discovered that the answer could be yes. For a large galaxy like the Milky Way, dark energy starts to outweigh gravity at distances beyond about 1.6 million light-years. At such a distance, dark energy would not be expected to shape the galaxy itself, but it could repel other, smaller galaxies, thereby explaining why the Milky Way has fewer satellite galaxies than theorists expect.
