Einstein Ring: Altieri’s Ring Found in Galaxy NGC 6505
Why in the news
Europe’s Euclid space telescope revealed a complete Einstein ring around a nearby galaxy, showing how new instruments can uncover hidden features even in well-studied galaxies.
Key facts
- Found by the Euclid mission of the European Space Agency (ESA) in September 2023.
- Host lens: galaxy NGC 6505, about 590 million light years from Earth.
- Named Altieri’s Ring after Bruno Altieri, who spotted it in blurry test images; sharper images confirmed it.
- The background galaxy being lensed is 4.5 billion light years away; only five other lenses are known at a similar distance.
- Confirmation: Keck Cosmic Web Imager (KCWI) data, March 2024.
- Mass of NGC 6505 was worked out using data from the Canada-France-Hawaii Telescope and the Dark Energy Spectroscopic Instrument; the lensed galaxy is old and no longer forms stars.
About Einstein rings
- An Einstein ring is a rare optical effect in which light from a distant object forms a circle around a massive object in front of it, produced by strong gravitational lensing.
- Under Einstein’s General Theory of Relativity, massive bodies curve space-time, like a heavy weight sagging a trampoline, and light follows the curved path.
- A perfect ring appears only when the distant source, the lensing galaxy and the observer line up exactly; otherwise several distorted images or arcs appear.
Significance
- Offers clues about how the universe is expanding.
- Helps test how gravity stretches space-time.
- Works as a natural magnifier for faint, far-off galaxies.
- Reveals unseen mass, supporting dark matter studies.
Exam angle
- Mission: Euclid (ESA); galaxy: NGC 6505; ring name: Altieri’s Ring.
- Related terms: gravitational lensing, General Relativity, dark matter.