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+--- Thread: Research Astronomers find rare Einstein cross with fifth image, revealing hidden dark matter (/thread-18797.html)
Astronomers find rare Einstein cross with fifth image, revealing hidden dark matter - C C - Sep 18, 2025
https://www.eurekalert.org/news-releases/1098554
INTRO: When Rutgers theoretical astrophysicist Charles Keeton first saw an unusual picture shared by his colleague, he was intrigued.
“Have you ever seen an Einstein Cross with an image in the middle?” his colleague Andrew Baker asked, referring to a rarely seen cosmic configuration.
Keeton hadn’t. The implications were enormous.
“I said, well, that’s not supposed to happen,” said Keeton, the Vice Provost for Experiential Learning at Rutgers University-New Brunswick. “You can’t get a fifth image in the center unless something unusual is going on with the mass that’s bending the light.”
An “Einstein Cross” is a rarely seen cosmic configuration, in which the light from a distant galaxy is bent by the gravity of galaxies in front of it, creating four images. But the extra image in this Einstein Cross pointed to “something unusual,” which turned out to be a massive, hidden halo of dark matter. The existence of this invisible structure could only be inferred through careful computer modeling and analysis.
The discovery, made by an international team that includes Keeton, Baker and Rutgers graduate student Lana Eid, is now being published in The Astrophysical Journal... (MORE - details, no ads)