ESA/Hubble Picture of the Week Prompts New Understanding of Einstein Ring.
Dernière mise à jour : 26 sept. 2021
In December 2020 the ESA/Hubble team published a stunning view from the NASA/ESA Hubble Space Telescope of one of the most complete Einstein rings ever discovered. This observation has since been used to develop a lensing model to study the physical properties of the lensed galaxy. Scientists have successfully measured the distance to the object and determined the magnification factor to be 20, which effectively makes Hubble’s observing capability equivalent to that of a 48-metre telescope.
Zoom into GAL-CLUS-022058s
In December 2020 ESA/Hubble publisehed an image in the Picture of the Week series depicting GAL-CLUS-022058s, located in the southern hemisphere constellation of Fornax (The Furnace). The image shows the largest and one of the most complete Einstein rings ever discovered, and was nicknamed the "Molten Ring'' by the Hubble observation’s Principal Investigator, which alludes to its appearance and host constellation.
First theorised to exist by Einstein in his general theory of relativity, this object’s unusual shape can be explained by a process called gravitational lensing, which causes light shining from far away to be bent and pulled by the gravity of an object between its source and the observer. In this case, the light from the background galaxy has been distorted into the curve we see by the gravity of the galaxy cluster sitting in front of it. The near exact alignment of the background galaxy with the centre of the galaxy cluster, seen in the middle of this image, has warped and magnified the image of the background galaxy into an almost perfect ring. The gravity from the galaxies in the cluster is soon to cause additional distortions.
A team of European astronomers have now used a multi-wavelength dataset, which includes inputs from the NASA/ESA Hubble Space Telescope and this featured image, to study this Einstein ring in detail. Archival data from the European Southern Observatories's VLT FORS instrument determined the redshift value of the lensed galaxy.