ALMA Gravitational Lens Image Reveals Hidden Galaxy

A dwarf, or dark galaxy, was discovered to be lurking around 4 billion light-years away from earth. The team of researchers and astronomers from the University of Illinois discovered this when they noticed a subtle distortion in the image from the gravitational lens SDP.81.

Hidden dwarf dark galaxy discovered 4 billion light years away from Earth. https://t.co/mvAhZSfgLp pic.twitter.com/0B7OfeLsoG

— ABC News (@ABC) April 19, 2016

This came as part of a campaign to test the new Atacama Large Millimeter/submillimeter Array (ALMA), an observatory in Chile run by an international partnership of different science organizations. One of these images was that of an Einstein ring, which was produced by a foreground galaxy that bended the light emitted by another smaller galaxy nearly 12 billion light-years away.

This light-bending phenomenon, according to Space Daily, is called gravitational lensing and was previously predicted by Einstein's general theory of relativity. It also offers a powerful tool for those who are studying galaxies and are too far away to observe.

Detailed analysis of the image showed signs of a hidden dwarf galaxy discovered in the halo of the nearer one. Because of its proximity to the larger galaxy, its mass and its lack of optical data made scientists think that they discovered a dim dwarf galaxy dominated by dark matter.

Theories suggest that the dark matter that made up about 80 percent of the mass of the universe is made up of particles that don't necessarily interact with visible light of electromagnetic radiation. However, they do have appreciable mass, which is how they can be identified by their gravitational influence -- and how the hidden galaxy was found.

Astronomy.com noted, however, that the majority of the dwarf galaxies may not be seen due to the fact that they are composed mainly of invisible dark matter. Yashar Hezaveh from the Stanford University in California noted that ALMA has changed that, as the technology has been doing its task fairly well. He and his team are confident of ALMA's ability to detect these dwarf galaxies in the future.