Discover the darkest galaxy in the universe

The research team, led by Yale University astronomer, has discovered the darkest material-filled galaxy ever known.

This galaxy, called Segue 1, is one of 24 small satellite galaxies orbiting our Milky Way galaxy. The Milky Way is one billion times brighter than this faint galaxy, according to the team's results, published in the upcoming issue of The Astrophysical (Ap). Despite the small number of visible stars, Segue 1 is thousands of times larger than it looks, indicating that most of its mass is made up of dark matter. Marla Geha, professor of astronomy at Yale and the lead author of the article said: 'This object is interesting. Segue 1 is a special example of a galaxy that contains only a few hundred stars, but has a large mass. '

Geha, along with colleague Josh Simon at the California Institute of Technology, observed half of dwarf satellite galaxies orbiting the Milky Way. These objects are very faint and contain only a small number of stars so they were originally mistaken for a globular star cluster - a very close cluster of stars orbiting our galaxy. However, after analyzing the light coming from these objects with the Keck telescope in Hawaii, Geha and Simon determined that these objects were galaxies, albeit very faint.

Segue 1 fades more than 50 times the upper cluster but has a mass of 1,000 times, indicating that most of its mass is made up of dark matter (Photo: Sloan Digital Sky Survey)

If only looking at the light emitted from these faint galaxies, Geha and her colleagues think they will have a small mass. However, they found that they were 100 to 100 thousand times larger than what was expected. The invisible dark matter is the cause of this difference.

Although dark matter does not emit or absorb light, scientists can measure its gravitational effect on ordinary matter, dark matter accounts for about 85% of the weight in the universe. Faint galaxy detection like Segue 1, filled with dark matter, provides clues to galaxy formation and development, especially at the smallest scale.

Geha said: 'These dwarf galaxies provide a great deal of knowledge about galaxies. For example, different theories about galaxy formation have different predictions about the number of dwarf galaxies and large galaxies. So comparing numbers is important '.

It was only recently that astronomers discovered the abundance of dwarf galaxies as these satellites, thanks to projects such as the Sloan Digital Sky Survey, detailing the vast night sky areas. In the last two years, the number of dwarf galaxies orbiting the Milky Way is known to double,

Geha predicts astronomers will discover even more as they continue to screen new data. She said: 'The galaxies believed to be bright today were the darkest galaxies we know of. This is like a new institution, the story begins to be revealed. '

The author of the article includes Marla Geha (Yale University), Beth Willman (Harvard-Smithsonian Center for Astrophysics), Joshua D. Simon (California Institute of Technology), Louis E. Strigari (University of California) , Irvine), Evan N. Kirby (University of California, Observatory Santa Cruz and Lick), David R. Law (California Institute of Technology), and Jay Strader (Harvard-Smithsonian Center for Astrophysics).