Such observations could help scientists pinpoint the nature of dark matter, which is believed to make up the vast majority of mass in the universe.
"[The dark matter is] distributed in a way that's different than the way visible matter is distributed—it's more extended; it's like a fuzzy halo around the stars," Tommaso said.
However, the distribution is not random. Rather, there is a relationship between the dark matter and the visible matter.
"The fact that we see this regularity tells us that there is some cross-talk between the two components," he said.
While previous research had suggested such a relationship may exist, astronomers still lack a simple explanation for it, Tommaso added.
Detecting Dark Energy
If researchers can find more double Einstein rings, they can compare the radius of the rings to better understand dark energy, Tommaso added.
Dark energy is a poorly understood force that is accelerating the expansion of the universe.
But understanding it is vital, since scientists calculate that there is about three times as much dark energy in the universe as there is dark matter and normal matter combined.
"The ratio of the diameters of the rings tells you something about how the universe expanded and so about dark energy," Tommaso said.
Meanwhile, the geometry of the two Einstein rings has allowed his team to measure the mass of the middle galaxy to about a billion times the mass of our sun. This indicates that the galaxy is a relatively small galaxy, known as a dwarf galaxy.
The dwarf is about six billion light-years away—the first dwarf galaxy accurately measured at such a distance, the researchers point out.
The nearest galaxy in the trio is about 2 billion light-years away from Earth, while the rear galaxy is about 11 billion light-years distant.
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