When astronomers detected a strange signal in a massive galaxy cluster millions of light years from Earth, they knew they had stumbled upon something big.
"I couldn't believe my eyes," Esra Bulbul, of the Harvard Center for Astrophysics, said in a written statement. "What we found, at first glance, could not be explained by known physics."
Just check out the video above, released this week by Science@NASA, to learn more.
In 2012, Bulbul and her colleagues examined data collected by NASA's Chandra X-Ray Observatory on the Perseus Cluster, an array of thousands of galaxies in the constellation Perseus. The Perseus Cluster is surrounded by a cloud of superheated gas, which contains ions that each emit their own "line" in the x-ray spectrum.
When the astronomers analyzed the cluster's "spectral signature," they found a mysterious spike that they couldn't explain.
"A line appeared at 3.56 keV (kilo-electron volts) which does not correspond to any known atomic transition," Bulbul said in the statement. "I have re-analyzed the data; split the data set into different sub groups; and checked the data from four other detectors on board two different observatories. None of these efforts made the line disappear."
The astronomers believe the emission may result from the decay of so-called sterile neutrinos, hypothetical particles that may make up dark matter, a mysterious substance that constitutes 80 percent of the mass of universe.
“We know that the dark matter explanation is a long shot, but the pay-off would be huge if we're right,” Bulbul said in an earlier statement released by NASA last month. “So we're going to keep testing this interpretation and see where it takes us.”