FILE: The European Space Agency released the first full-color images taken by the Euclid telescope, a new spacecraft designed to study dark matter. (Video credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi)
While testing out its dark matter detective, European Space Agency scientists saw a cosmic phenomenon named after famed physicist Albert Einstein: an Einstein ring.
ESA’s Euclid spacecraft launched in July 2023 from Florida to create a 3D map of the Universe and seek out the origin of the accelerating expansion known as dark energy.
During its testing phase last year, the team obtained deliberately blurry images from the space telescope, but scientists immediately saw something exciting even without clarity.
A close-up of the Einstein ring around galaxy NGC 6505.
Einstein’s general theory of relativity states that light will bend around objects in space, focusing on the light like a giant magnifying lens. According to the ESA, an Einstein ring is a strong example of this magnification process known as gravitational lensing, which can sometimes be used to see light from distant galaxies that are usually hidden. If the alignment is just right, the light from a distant source will form a ring around the object in the foreground.
Euclid Archive Scientist Bruno Altieri saw this when looking at those first images more than two years ago.
“Even from that first observation, I could see it, but after Euclid made more observations of the area, we could see a perfect Einstein ring,” Altieri said in an ESA blog. “For me, with a lifelong interest in gravitational lensing, that was amazing.”
A Euclid image of a bright Einstein ring around galaxy NGC 6505.
The bright ring was seen around galaxy NGC 6505, considered to be in our cosmic neighborhood at about 590 million light-years from Earth. The ESA said this is a “stone’s throw in cosmic terms.”
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“I find it very intriguing that this ring was observed within a well-known galaxy, which was first discovered in 1884,” ESA Euclid Project Scientist Valeria Pettorino said. “The galaxy has been known to astronomers for a very long time. And yet, this ring was never observed before. This demonstrates how powerful Euclid is, finding new things even in places we thought we knew well.”
The background galaxy is much farther away, at 4.62 billion light-years, and doesn’t have a name yet because this is the first observation, thanks to Euclid’s powerful abilities. According to the ESA, less than 1,000 strong lenses like this are known, and even fewer have been seen in high resolution.
While the Einstein ring was an exciting find, Euclid’s primary mission is to search for weak gravitational lensing to map more than a third of the sky and find the origin of the accelerating expansion known as dark energy.