The active star-forming galaxy called SDP.81 was discovered in 2010 by the Herschel Space Observatory. Lensed by a massive and comparatively nearby foreground galaxy, it is located approximately 12 billion light-years away from Earth. New images of the galaxy, captured by the Atacama Large Millimeter/submillimeter Array (ALMA), reveals almost perfect Einstein ring.
The images have the highest resolution ever captured with the telescope. In case of SDP.81, the galaxy and the foreground galaxy line up in a perfect manner due to which the light from the more distant one appears as a nearly complete circle when seen from Earth. According to the scientists, it represents a rare expression of gravitational lensing, which was first predicted by Albert Einstein in his theory of general relativity.
Gravitational lensing refers to a phenomenon in which a huge galaxy or a group of galaxies bends the light emerging from a more distant galaxy. This results in the formation of a highly magnified but distorted image. Catherine Vlahakis, ALMA deputy program scientist, stated “Gravitational lensing is used in astronomy to study the very distant, very early universe because it gives even our best telescopes an impressive boost in power.”
The new ALMA images show surprising level of detail and will help astronomers to reassemble the information hidden in the distorted image. In this way, the scientists will be able to reconstruct the true image of the distant galaxy. The images may also uncover more details about bending of light by the gravitational lens.