Dark Matter Signal...

This ellipse shows a region of sky where a galaxy made of dark matter is thought to exist.

Astronomers may finally have detected a signal of dark matter, the mysterious and elusive stuff thought to make up most of the material universe.

While poring over data collected by the European Space Agency's XMM-Newton spacecraft, a team of researchers spotted an odd spike in X-ray emissions coming from two different celestial objects — the Andromeda galaxy and the Perseus galaxy cluster.

The signal corresponds to no known particle or atom and thus may have been produced by dark matter, researchers said.

Space.com: Cosmic Mystery Solved? Possible Dark Matter Signal Spotted, Mike Wall
Eureka Alert: Researchers detect possible signal from dark matter