NASA’s Spitzer Space Telescope (SST) has captured mesmerizing blue-black image of galaxy cluster Abell 2744, commonly known as Pandora’s Cluster. The cluster appears magnified due to gravitational lensing effect of its own gravity.
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. The amount of bending is one of the predictions of Albert Einstein’s general theory of relativity.
In the image, the fuzzy blue spots are massive galaxies especially at the center of the cluster, but astronomers will be poring over the images in search of the faint streaks of light created where the cluster magnifies a distant background galaxy. In this image, light from Spitzer’s infrared channels is colored blue at 3.6 microns and green at 4.5 microns.
NASA’s Chandra X-ray observatory and Hubble Space Telescope are also monitoring this Pandora Cluster. Astronomers have used Abell 2744 for magnifying images of more distant background galaxies. The more distant galaxies appear as they did longer than 12 billion years ago, not long after the big bang.
The above image captured by Hubble Space Telescope reveals almost 3,000 of these background galaxies interleaved with images of hundreds of foreground galaxies in the cluster. Their images not only appear brighter, but also smeared, stretched and duplicated across the field. Because of the gravitational lensing phenomenon, the background galaxies are magnified to appear as much as 10 to 20 times larger than they would normally appear. Furthermore, the faintest of these highly magnified objects is 10 to 20 times fainter than any galaxy observed previously. Without the boost from gravitational lensing, the many background galaxies would be invisible.
Moreover, JPL manages the Spitzer Space Telescope (launched back in 2003) mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.