The James Webb Space Telescope (JWST) has facilitated the discovery of a distant galaxy enveloped by what is referred to as an "Einstein Ring". This ring, resulting from a gravitational lensing phenomenon, has revealed an exceptionally dense galaxy.
The JWST-ER1 Einstein Ring discovered in September 2023.
Credit: P. van Dokkum et al., Nature Astronomy accepted, 2023
Einstein Rings occur when the light from a distant object is distorted by the significant mass of an object positioned between it and the observer. This distortion is caused by the curvature of space-time around the massive object, thereby bending the light. The James Webb Space Telescope has identified a particular structure named JWST-ER1, consisting of JWST-ER1r, the luminous ring, and JWST-ER1g, the foreground object distorting the light.
The object JWST-ER1r is the most distant object ever observed through gravitational lensing effects. Although this object is incredibly massive, estimated at 650 billion solar masses, scientists have discovered that a large portion of this mass is dark matter, a form of matter that does not interact with light and constitutes about 85% of all the matter in the Universe.
Researchers have noted an unusual density for JWST-ER1g. They suggest that this density could be explained by the presence of a dark matter halo compressed by the collapse of ordinary matter within this halo, thus increasing its density.
Credit: NASA/James Webb Space Telescope/van Dokkum et al.
A study published on April 11 in the journal
The Astrophysical Journal Letters suggests that this compression of dark matter explains the abnormal density of JWST-ER1g. The authors of the study, led by Demao Kong from the University of California at Riverside, believe that their numerical models support this hypothesis.
This discovery is not the first observation of an Einstein Ring by the James Webb Space Telescope, but it marks a significant advancement in understanding the distribution and behavior of dark matter in the Universe.