A newly discovered “dark flow” appears to carry clusters of galaxies toward a point in the southern sky, a new study suggests.
As if dark matter and dark energy weren’t confusing enough, researchers detected what they have dubbed dark flow while surveying 700 galaxy clusters — each containing hundreds to thousands of galaxies — within a radius of approximately 1 billion light-years. On average, the clusters appeared to move in a uniform direction at about 1,000 kilometers per second.
While no one knows the cause of the motion, the scientists suggest that whatever it is may no longer lie within the visible universe. The work appears online in two separate papers, one to appear in the Oct. 20 Astrophysical Journal Letters and the other in an upcoming Astrophysical Journal.
“We expected to find something completely different,” says Alexander Kashlinsky, an astrophysicist at NASA’s GoddardSpaceFlightCenter in Greenbelt, Md. “It’s basically a slope across the universe,” in a direction somewhere between the constellations of Centaurus and Vela.