Astronomers performing operations with Gran Telescopio Canarias (GTC) discovered an optical Einstein Ring (ER). The finding was made by analyzing data from a Dark Energy Camera and deriving spectroscopic redshifts from both, the source-a starburst galaxy and the lens-a luminous red galaxy.
The ER is an almost circular ring with 300° in circumference and 4.5 arc seconds in diameter. The starburst galaxy, from where the source light is emitted, was found at a redshift of z=1.165, while the lens, the luminous red galaxy, is at z=0.581. Utilizing the measured redshifts and Einstein radius (E=2.16 arc seconds) of the system, astronomers calculated the total mass of the system producing the gravitational lens at 1.86 plus or minus 0.23 x 10 to the power of 12 M.
An Einstein ring consists of the deformation of light from a source, such as a star, galaxy or any other astronomical object, when it is passing through another massive astronomical body. Instead of light travelling in a straight line through space, it is bent by the gravitational effects of a massive body, distorting space-time. An ER is one of many types of these rings, with the characteristics that an ER is almost circular.
This type of phenomena describes the bending of light from a distant source-cluster of stars, galaxy-in the universe, as it travels in the direction of an observer. For this phenomenon to be observable, there needs to be a source of light, a lens in the middle and an observer. If the three elements are aligned in a straight line, the source light will show as a ring (ER) around the massive object lens; however, if they´re not aligned, there will only be portions of an arc around the objective massive lens.
While Einstein’s theory of relativity predicted this event, which is a particular case of these phenomena, gravitational lensing, explains that instead of light traveling in a straight line, it is distortioned by a massive object, including a black hole or galaxy, curving space and time around them.