Gravitational lensing provides unique insights into astrophysics and cosmology. Using ESO’s Very Large Telescope, astronomers have discovered a new strong lensing system, DESI-253.2534+26.8843. This system consists of a massive elliptical galaxy surrounded by four blue images forming a rare Einstein Cross pattern.
DESI-253.2534+26.884. Image credit: ESO / Cikota et al.
Strong gravitational lensing occurs when a massive object warps spacetime and causes the path of light from a well-aligned distant source to bend, typically resulting in multiple images.
These systems are a powerful tool for astrophysics and cosmology.
They have been used to study how dark matter is distributed in galaxies and clusters.
When the alignment is nearly perfect and the lens mass has an elliptical distribution, the background source would appear as quadruply lensed.
These systems are prized as they provide the strongest constraint on the lens mass distribution.
One specific example of quadruply lensed system is the Einstein Cross, where four distinct images of the background source form a cross-like pattern with a high degree of symmetry.
The strong gravitational lens system DESI-253.2534+26.884 was discovered in the DESI Legacy Imaging Surveys data using neural networks.
“The four ‘petals’ in DESI-253.2534+26.884 are images of a distant galaxy hidden behind the orange galaxy at the center,” said Gemini Observatory astronomer Aleksandar Cikota and colleagues.
“Something very fascinating happens to allow us to detect the light from this hidden object: the galaxy at the center acts as a gravitational lens, bending the light emitted from the distant galaxy around it.”
“As a result, we see several images of the distant galaxy, distorted and magnified.”
“In the special configuration of these two galaxies, the hidden one appears as four images around the central ‘lens’ galaxy, forming a cross-like (or flower-like) pattern dubbed an Einstein Cross.”
“Gravitational lensing thus allows us to discover hidden galaxies that would be otherwise invisible to us.”
DESI-253.2534+26.884 (center). Image credit: ESO / Cikota et al.
The astronomers observed DESI-253.2534+26.884 in May 2023 with the Multi Unit Spectroscopic Explorer (MUSE), mounted at UT4 of ESO’s Very Large Telescope (VLT) on Cerro Paranal in Chile.
“MUSE splits the light coming from every point within the area being observed into a rainbow or spectrum, which provides us with a wealth of information about the objects within the field of view,” they explained.
“Our results show that the distant galaxy is forming stars at a rapid rate.”
“Since light left the galaxy when the Universe was about 20% of its current age, studying it provides clues about how galaxies formed in the early Universe.”
The results appear in the Astrophysical Journal Letters.
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Aleksandar Cikota et al. 2023. DESI-253.2534+26.8843: A New Einstein Cross Spectroscopically Confirmed with Very Large Telescope/MUSE and Modeled with GIGA-Lens. ApJL 953, L5; doi: 10.3847/2041-8213/ace9da
