World Science
Signs of dark matter found?
Signs of dark matter found?
Telltale signs may have turned up of a mysterious substance that pervades the universe but has never been seen, astronomers say.
The “dark matter” is believed to make up five-sixths of the physical material in the universe, but has revealed no sign of its existence other than through its gravitational pull. For decades, physicists have tried to figure out just what the stuff is.
Some theories hold that signature signs of dark matter could be detected when particles of the stuff meet and annihilate each other. These events would result in emissions of electrically charged particles.
Such a sign of dark matter annihilation may have been detected high above the skies of Antarctica, according to an international research team. The group reports the findings in the Nov. 20 issue of the research journal Nature.
The investigators recorded what they said was an unexpectedly high amount of the charged particles, called electrons, at energies consistent with theoretical predictions about the dark matter.
The specific dark matter “annihilation signature” is consistent with the idea that dark matter consists of components called Kaluza-Klein particles, according to the research group. These particles emerge from theories of the universe involving extra dimensions beyond those which we can normally detect—theories that in turn have been invoked to show that the various forces of nature could possess an underlying unity.
However, the detected electrons could also come from celestial objects unrelated to dark matter, such as so-called pulsars or microquasars, the team noted.
The detections were made using a high-altitude balloon-borne device called an advanced thin ionization calorimeter.
Because, as Einstein showed, matter and energy are ultimately equivalent, dark matter would also be a part of the energy in the universe. Cosmologists estimate that dark matter comprises 23 percent of all energy in the cosmos. An equally mysterious “dark energy,” which drives galaxies apart, is thought to take up another 73 percent or so. Ordinary, visible matter is believed to represent only four percent of the total energy.
The team consisted of researchers from Purple Mountain Observatory in Nanjing, China; the Marshall Space Flight Center in Huntsville, Ala.; the University of Maryland; Moscow State University; and Louisiana State University.