'Dark Matter' Solves Mystery of the Missing Galaxies

Small, ultrafaint "hobbit" galaxies more than 10,000 times smaller than the Milky Way, found hovering around the galaxy are comprised almost entirely of dark matter, a new study confirms according to a Space.com report by Ker Than. Until recently, only 11 such companion galaxies have been found.

Unknown in make up or where it came from, dark matter is thought to provide the universe with the extra gravity that it needs to keep from spinning out of control. The gravity exuded by stars that dwarf our own sun, apparently count for very little in the great scheme of things. The best that scientists can come up with is the belief that dark matter is a simple elementary particle found throughout the cosmos.

According he Nov. 10 issue of Astrophysical Journal, the "Cold Dark Matter" model, which explains the growth and evolution of the universe, large galaxies such as our Milky Way should be surrounded by a swarm of up to several hundred smaller "dwarf" galaxies, which contain very few, if any, stars and are made up mostly of dark matter.

To explain this so-called Missing Dwarf Galaxy problem, theorists have suggested that the majority of dwarf galaxies contain very few, if any, stars and are instead made up mostly of dark matter.

Earlier this year, members of the Sloan Digital Sky Survey team announced they had discovered eight small and extremely faint galaxies in our Local Group of galaxies that might belong to this bizarre class of "dark" galaxies.

Using the Keck II telescope in Hawaii, Joshua Simon of Caltech and Marla Geha of the Herzberg Institute of Astrophysics in Canada conducted follow-up studies to calculate the mass of the hobbit galaxies based on the speeds at which stars inside them moved.

Space.com reports that the team also found that the mass of the galaxies was about 100 times more than what would be expected from the mass of their stars alone. "And so the rest of it has to be in some other kind of matter," Simon added. "Our work narrows the gap between the Cold Dark Matter theory and observations by significantly increasing the number of Milky Way dwarf galaxies and telling us more about the properties of these galaxies."

Posted by Casey Kazan.