Astronomers using NASA's Chandra X-ray Observatory to explore the Perseus Cluster, a swarm of galaxies approximately 250 million light years from Earth, have observed the spectral line that appears not to come from any known type of matter. The signal they received can not be explained by known physics but they say it shifts suspicion to the dark matter.

Perseus Cluster a collection of galaxies and one of the most massive known objects in the Universe, immersed in an enormous 'atmosphere' of superheated plasma. It is approximately 768 000 light years across.

"I couldn't believe my eyes," says Esra Bulbul of the Harvard Center for Astrophysics.  "What we found, at first glance, could not be explained by known physics."

"The cluster's atmosphere is full of ions such as Fe XXV,  Si XIV, and S XV.  Each one produces a 'bump' or 'line' in the x-ray spectrum, which we can map using Chandra. These spectral lines are at well-known x-ray energies."