What can the Milky Way teach us about the formation of the universe? Quite a bit it appears.
Seeking out galaxies similar to the Milky Way in terms of luminosity and distance to other bright galaxies, scientists discovered that only four percent of other galaxies resemble the Milky Way.
Using images from the Sloan Digital Sky Survey (SDSS), astrophysicist Risa Wechsler and her team at Stanford University studied over 20,000 galaxies similar to the Milky Way and the galaxies near them to develop a sort of "census" of the galaxies.
The scientists sought out galaxies that have celestial satellites similar to the Large and Small Magellanic Clouds. The clouds are actually dwarf galaxies that orbit the Milky Way, and other groupings like this one are “unusual” in the universe, according to Wechsler.
"We are interested in how the Milky Way fits into the broader context of the universe", said Wechsler. "This research helps us understand whether our galaxy is typical or not, and may provide clues to its formation history."
In addition to looking at images from the SDSS, Wechsler and her group compared the images to computer simulations that recreated the universe under different sets of conditions. This research helped determine how theories of the universe’s formation match how the universe currently looks.
"Comparing the 'fake' and 'real' universes is how we discriminate between successful and unsuccessful theories," said Neil Sharp of the National Science Foundation’s Division of Astronomical Studies. Sharp was not involved in the research.
The findings lend support to the theory of galaxy formation called the Cold Dark Matter theory. The theory assumes that unobservable (dark) electromagnetic radiation whose particles move slowly (cold) influence the distribution of galaxies in space as well as the expansion of the universe.
"Future surveys will allow us to extend this study to even dimmer satellite galaxies, to build a full picture of the formation of our galaxy," said Wechsler.
The findings were published in the May 20 issue of Astrophysical Journal.
On the Web: How Common are the Magellanic Clouds?