Dwarf Galaxies Don't Fit the Standard Model of the Universe: Structure of Galaxies Questioned

It turns out that there may be no place in the universe for dwarf galaxies--at least when it comes to mapping them. Astronomers have found that dwarf galaxies that orbit the Milky Way and the Andromeda galaxies defy the accepted model of galaxy formation and do not fit into the current model.

"The model predicts that dwarf galaxies should form inside small clumps of dark matter and that these clumps should be distributed randomly about their parent galaxy," said David Merritt, one of the researchers, in a news release. "But what is observed is very different. The dwarf galaxies belonging to the Milky Way and Andromeda are seen to be orbiting in huge, thin disk-like structures."

In fact, the researchers found that there are serious issues with the idea that satellite galaxies support to standard model. Earlier papers found structures in the simulations that didn't really look like observed planar structures.

"Either the selection of model satellites is different from that of the observed ones, or an incomplete set of observational constraints has been considered, or the observed satellite distribution is inconsistent with basic assumptions," write the researchers in a news release. "Once these issues have been addressed, the conclusions are different: Features like the observed planar structures are very rare."

The standard cosmological model is the frame of reference for many generations of scientists. The fact that it's now being called into question may mean that there could be some major changes in the future.

"Our conclusion tends to favor an alternate, and much older, model: that the satellites were pulled out from another galaxy when it interacted with the Local Group galaxies in the distant past," said Merritt in a news release. "This 'tidal' model can naturally explain why the observed satellites are orbiting in thin disks."

The findings are published in the journal Monthly Notices of the Royal Astronomical Society.