NASA: Mysterious signal is enigmatic, perplexing

NASA mysterious signal: Detected by two NASA spacecraft, X-ray emissions of unknown origin could lend insight into dark matter, a mysterious substance thought to compose more than 80 percent of all matter in the known universe.

X-ray: NASA, CXC, SAO, E.Bulbul, et
Perseus Cluster is seen in an image that uses data representing more than 17 days of observation time over 10 years.

Two spacecraft have detected a possible signal of dark matter, the mysterious, invisible stuff that makes up most of the material universe.

NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite spotted a spike of X-ray emission coming from more than 70 different galaxy clusters. While the origin of the X-rays remains unclear at the moment, they could be generated by the decay of a certain type of dark-matter particle, scientists said.

"We know that the dark matter explanation is a long shot, but the payoff would be huge if we're right," study lead author Esra Bulbul, of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, said in a statement. "So we're going to keep testing this interpretation and see where it takes us." [Gallery: Dark Matter Throughout the Universe]

Dark matter is so named because it neither absorbs nor emits light, making it impossible to observe directly. But astronomers know that dark matter exists because it interacts gravationally with the "normal" matter we can see and touch.

In fact, dark matter is thought to make up more than 80 percent of all matter in the universe. But scientists don't know exactly what it is.

Over the years, researchers have proposed a number of exotic particles as candidate components of dark matter, including weakly interacting massive particles (WIMPs), axions and sterile neutrinos — a hypothetical type of neutrino that emits X-rays when it decays.

It's possible that the signal observed by Chandra and XMM-Newton was produced by sterile neutrinos, researchers said. But that's far from a sure thing, they stressed, since the detection of the X-ray spike pushed both observatories to their sensitivity limits.

"We have a lot of work to do before we can claim, with any confidence, that we've found sterile neutrinos," co-author Maxim Markevitch, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. "But just the possibility of finding them has us very excited."

"Normal" matter in the galaxy clusters may also be responsible for the emission (if it is indeed real and not an instrument artifact). But this interpretation doesn't mesh well with current thinking about galaxy clusters and the atomic physics of hot gases, researchers said.

"Our next step is to combine data from Chandra and JAXA's [the Japanese Aerospace Exploration Agency's] Suzaku mission for a large number of galaxy clusters to see if we find the same X-ray signal," said co-author Adam Foster, also of CfA.

"There are lots of ideas out there about what these data could represent," Foster added. "We may not know for certain until Astro-H launches, with a new type of X-ray detector that will be able to measure the line with more precision than currently possible."

Astro-H is an X-ray observatory being developed by JAXA. It's scheduled to be launched to Earth orbit next year.

The new paper was published in the June 20 issue of The Astrophysical Journal.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook orGoogle+. Originally published on Space.com.

Copyright 2014 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.