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Dwarf dark galaxy hidden in ALMA gravitational lens image

14 April 2016 Astronomy Now

Subtle distortions hidden in a stunning Atacama Large Millimetre/submillimetre Array (ALMA) image of the gravitational lens SDP.81 are telltale signs that a dwarf dark galaxy is lurking in the halo of a much larger galaxy nearly 4 billion light-years away. This discovery could help astronomers address important questions on the nature of dark matter.