'600 million light-years away': ESA's Euclid Telescope discovers nearest known Einstein ring
Produced by Tarun Mishra
Produced by Tarun Mishra
Astronomers have discovered the nearest known Einstein ring, a gravitational lensing phenomenon where light from a distant galaxy is bent by the gravity of a closer galaxy. Initially thought to be a single galaxy, the ring was first observed over a century ago.
The effect was first described by Albert Einstein in his theory of general relativity. At the time, he considered it impossible to observe, but advances in telescopic technology have now confirmed the presence of multiple such rings.
Researchers identified that the elliptical galaxy NGC 6505, located 600 million light-years from Earth, is bending the light of another galaxy positioned around 6 billion light-years away. This realisation came during an analysis of early data from the Euclid telescope.
Bruno Altieri of the European Space Agency spotted the ring while validating initial testing data from the Euclid telescope. The discovery was unexpected, as such a striking Einstein ring was estimated to be a rare find across the entire survey.
Due to its proximity and Euclid’s imaging capabilities, the ring appears brighter and clearer than most previously known Einstein rings. The surrounding faint orange light represents the foreground lensing galaxy, making the structure distinctly visible.
The close distance of the ring allows astronomers to measure the lensing galaxy’s mass using two methods: the bending of light and the speed of its stars. According to general relativity, both values should match, providing an opportunity to verify the theory.
Initial measurements indicate a slightly higher mass than expected based on the estimated number of stars, suggesting dark matter may be concentrated at the galaxy’s centre. Further observations of more Einstein rings are needed to confirm this possibility.
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