NASA's Hubble Space Telescope captured the first-ever picture of a group of five star-like images of a single distant quasar.
The multiple-image effect is produced by a process called gravitational lensing, in which the gravitational field of a massive object -- in this case, a cluster of galaxies -- bends and amplifies light from an object -- in this case, a quasar – farther behind it.
Although many examples of gravitational lensing have been observed, this "quintuple quasar" is the only case so far in which multiple quasar images are produced by an entire galaxy cluster acting as a gravitational lens.
The background quasar is the brilliant core of a galaxy. It is powered by a black hole, which is devouring gas and dust and creating a gusher of light in the process. When the quasar's light passes through the gravity field of the galaxy cluster that lies between us and the quasar, the light is bent by the space-warping gravity field in such a way that five separate images of the object are produced surrounding the cluster's center. Four of these appear as white star-like images. The fifth quasar image is embedded to the right of the core of the central galaxy in the cluster. The cluster also creates a cobweb of images of other distant galaxies gravitationally lensed into arcs.
The galaxy cluster creating the lens is known as SDSS J1004 4112 and was discovered in the Sloan Digital Sky Survey. It is one of the more distant clusters known (seven billion light-years away), and is seen as it appeared when the universe was half its present age.
Credit: NASA, ESA, K. Sharon (Tel Aviv University) and E. Ofek (Caltech)