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Phoenix666 [soylentnews.org] writes:

New analysis of an image [futurity.org] taken by the ALMA telescope [almaobservatory.org] in Chile reveals evidence that a dwarf dark galaxy—a tiny halo companion of a much larger galaxy—is lurking nearly 4 billion light-years away.

This discovery paves the way for ALMA to find many more such objects, which could help astronomers address important questions on the nature of dark matter.

In 2014, as part of ALMA’s Long Baseline Campaign, astronomers studied a variety of astronomical objects to test the telescope’s new high-resolution capabilities. One of these experimental images was that of an Einstein ring, which was produced by a massive foreground galaxy bending the light emitted by another galaxy nearly 12 billion light-years away.

This phenomenon, called gravitational lensing, was predicted by Einstein’s theory of general relativity, and it offers a powerful tool for studying galaxies that are otherwise too distant to observe. It also sheds light on the properties of the nearby lensing galaxy because of the way its gravity distorts and focuses light from more distant objects.

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