The Coma Galaxy Cluster. It appears to participate in the dark flow.
Dark flow is a peculiar velocity of galaxy clusters. The velocity of galaxies can be predicted by Hubble’s Law, but there is an unexplained(dark flow) in the direction of the Centaurus and Hydra constellations.
Standard cosmological models show that the motion of galaxy clusters should be randomly distributed in all directions, but a recent study found evidence of a 600–1000 km/s flow of clusters toward a 20-degree patch of sky. The scientists who conducted the study believe that the motion may be a remnant of no-longer-visible regions of the universe that have moved beyond our ability to see with current telescopes. Due to the inflation of the universe, telescopes cannot see events earlier than about 380,000 years after the big bang. This is equivalent to the particle horizon at 46 billion light years.
The Dark Flow is flowing in the direction of Centaurus and Hydra. That is the same direction of the Great Attractor, which is a gravitational mystery that was discovered in 1973. The Great Attractor was thought to originate from the Norma Cluster, but this study may reveal that the source of that attraction might lie even further away, and the Great Attractor is heading towards. The number of clusters affected seems to be 1,400 and it can be seen as far as 2.5 billion light years away.
One way to think of the Dark Flow is to picture a huge drain in a lake. As you float on top of the lake you can not see the slow drain of the water nor can you see the movement of the water. The surface looks flat and calm until you put several small items on the surface in different places and film their movement over a long period of time. When you watch the films you would see all of the objects moving to one point.
There are many scientists who disbelieve the results of the study and refute the Dark Flow. Nearly every advancement in science has met with skepticism. Only time and more science will tell.
We have written many articles about dark flow for Universe Today. Here’s an article about the universe’s expansion, and here’s an article about scientists detecting dark flow matter from the beyond the visible universe.
If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.
We’ve also recorded an episode of Astronomy Cast about galaxies. Listen here, Episode 97: Galaxies.
Sources:
NASA
NASA: Scientists Detect Cosmic ‘Dark Flow’ Across Billions of Light Years
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