Astronomers have recently found that besides the Milky Way and the Andromeda galaxies, there is another large galaxy in the universe being orbited by smaller dwarf galaxies in an orderly manner.
Centaurus A, which is located 13 million light-years away from Earth, serves as a parent galaxy to a system of satellite galaxies dispersed perpendicular to it in a narrow disc-shaped plane.
Out of these 16 satellite galaxies, 14 of them were observed to co-rotate around their parent galaxy following an organized motion pattern.
This discovery questions the lambda cold dark matter model that assumes satellite galaxy systems to be randomly scattered around a larger galaxy, with a chaotic movement similar to bees flying around a beehive.
Moreover, such formation should not even be detectable, as it was previously believed that other large galaxies are comprised mostly of invisible dark matter.
"This observational evidence suggests that something is wrong with standard cosmological simulations," stated an international team led by the University of Basel in a paper published Feb. 2 in the Science journal.
Investigating The Formation Of Centaurus A
To determine the movement of Centaurus A's satellite galaxy system, astronomers had to measure its tangential velocity, and such process takes a lot of time.
"You take a picture now, wait three years or more, and then take another picture to see how the stars have moved," explains coauthor Marcel Pawlowski, a Hubble Fellow at the University of California in Irvine.
Visibility of the system's plane from the Earth also plays a huge factor. Because of their proximity, observing the Milky Way and the Andromeda galaxies is relatively easier than Centaurus A, which satellite galaxies appeared faint.
Using such observations and measurements, astronomers then use specialized computers to create a virtual simulation of satellite galaxy systems.
Disproving The Standard Cosmological Model
Now that three galaxy systems have already been identified, the team believes there are a few more of them waiting to be discovered, and of these rare formations, they predict that only 0.5 percent have the same motion pattern as the Milky Way, Andromeda, and Centaurus A.
"Coherent movement seems to be a universal phenomenon that demands new explanations," said lead author Oliver Müller of the University of Basel's Department of Physics.
The standard cosmological model also falls short in providing an explanation for the development of these systems. Results of the paper, however, strongly supports the theory supposing that they are produced when a pair of large galaxies collide.