How does the Einstein Ring discovery help test Einstein's theory of general relativity?

This discovery provides a unique opportunity to test Einstein's theory of general relativity by measuring the mass of the lensing galaxy in two ways: by analyzing light bending patterns and by observing the velocity of stars within the galaxy. According to Einstein's theory, these two measurements should yield identical values. When researchers calculated the mass, they found it slightly higher than expected based on the estimated number of stars, revealing a discrepancy that may be attributed to dark matter clustering at the galaxy's center. This finding potentially confirms Einstein's predictions while simultaneously revealing the presence of dark matter, though further observations of similar lenses are needed to confirm this hypothesis.