Astronomers claim to have discovered a rich diversity of at least 67 gravitational lenses around a number of massive elliptical and lenticular-shaped galaxies in the distant Universe, using the Hubble Space Telescope.The strong lensing produced by massive galaxies is much more common than the usual giant “arc” gravitationally lensed galaxies that Hubble has previously observed; but they are generally more difficult to find as they extend over a smaller area and have a wide variety of shapes, the NASA said.Gravitational lensing occurs when light travelling towards earth from a distant galaxy is magnified and distorted as it encounters a massive object.These gravitational lenses often allow astronomers to peer much further back into the early universe than they would normally be able to. The massive objects that create the lenses are usually huge clusters of massive galaxies.“We typically see the gravitational lens create a series of bright arcs or spots around a galaxy cluster. What we are observing here is a similar effect but on much smaller scale — happening only around a single but very massive galaxy,” said lead astronomer Jean-Paul Kneib of the Laboratoire d’Astrophysique de Marseille.The lenses come from a recently completed, large set of observations as part of a huge project, named COSMOS, single 1.6 square degree field of sky (nine times the area of the full Moon) with several space-based and Earth-based observatories. Of the 67 gravitational lenses identified in the COSMOS survey, the most impressive lenses show the distorted and warped light of one or two background galaxies.At least four of the lenses give rise to Einstein rings, a complete circular image of a background galaxy, which is formed when the background galaxy, a massive foreground galaxy and the Hubble Space Telescope are all aligned perfectly.Hubble astronomers went through a unique process to identify these incredible natural lenses. First, possible galaxies were identified from a catalogue.“We then had to look through each individual image by eye and identify any potential strong gravitational lenses. Finally, checks were made to see if the foreground galaxy and the lensed galaxy were really different,” said co-researcher Cicile Faure.“With this sample of gravitational systems identified by the human eye, we now plan use the sample of lenses to train robot software to find more of these lenses across the entire Hubble image archive,” he said.
