Discovery of Altieri’s Einstein Ring: A Breakthrough in Space Observation

Sub: SCI

Sec: Space sector

Why in News

The Euclid space telescope, launched by the European Space Agency (ESA), has discovered a new Einstein ring in the galaxy NGC 6505.This discovery is significant as only five other gravitational lenses at similar distances have been found so far.

About Einstein Rings:

Albert Einstein, proposed that massive objects like galaxies bend light from distant objects due to their gravitational pull.
This phenomenon, known as gravitational lensing, results in arc-like structures around the foreground lens.
When the alignment of the background object, gravitational lens, and observer is nearly perfect, it forms a circular pattern known as an Einstein ring
The first Einstein ring was discovered in 1998, over 80 years after Einstein’s prediction.

Altieri’s Ring:

The Einstein ring was first observed in September 2023 by astronomer Bruno Altieri in an initial blurry image captured by Euclid.
Named Altieri’s Ring, this Einstein ring consists of the distorted images of another galaxy located 4.5 billion light-years away.
Altieri’s Ring is considered extraordinary because it has been observed in a well-studied, nearby galaxy—NGC 6505, located 590 million light-years from Earth.
Following the initial detection, additional observations were conducted using:
- Keck Cosmic Web Imager (KCWI) in March 2024, confirming the lensed nature of the images.
- Canada-France-Hawaii Telescope and Dark Energy Spectroscopic Instrument, verifying the mass and distance of NGC 6505 and the background galaxy.

Gravitational Lensing and General Relativity:

Einstein’s General Theory of Relativity states that massive objects distort spacetime, similar to how a heavy object deforms the surface of a stretched fabric.
This warping of spacetime alters the path of light, a phenomenon explained by physicist John Wheeler.
The foreground galaxy, acting as a gravitational lens, bends and magnifies the light from background sources, creating multiple distorted images.

Types of Gravitational Lensing:

Weak Lensing: Minor distortions in background objects’ shapes due to gravitational effects.
Strong Lensing: Multiple images of the background object are produced due to a strong gravitational field.
Einstein Rings: A special case of strong lensing where the light forms a nearly perfect ring around the lensing galaxy.

About Euclid Space Telescope:

It derives its name from the Greek mathematician Euclid of Alexandria.
This mission was part of ESA’s Cosmic Vision programme, aimed at exploring the origin and components of the Universe and the fundamental laws that govern it.
The spacecraft was equipped with a 1.2-metre-wide telescope and two instruments:
- A visible-wavelength camera (the VISible instrument): It sought tiny distortions in the shapes of distant galaxies from different points in time to highlight the interplay between the pull of gravity and the push of dark energy.
- A near-infrared camera/spectrometer (the Near-Infrared Spectrometer and Photometer): It observed how quickly galaxies were moving away from each other, providing scientists with insights into both dark energy and the workings of gravity.
The detectors of the near-infrared instruments were supplied by NASA, making the American agency an integral part of the Euclid Consortium.
It orbited 1.5 million kilometres above the Earth, and the telescope aimed to capture images at least four times sharper than ground-based ones.
The spacecraft had dimensions of approximately 4.7 metres in height and 3.7 metres in diameter.
It was launched atop a SpaceX Falcon 9 rocket
It will remain operational for a minimum of six years.”