January 20, 2012 20:23
Astronomers have discovered a galaxy made of dark matter. To search for an invisible galaxy, scientists have used the so-called lens Einstein — a method that allows you to find objects by their gravitational influence on the environment.
The existence of dark matter was postulated in 1930 by Swedish astronomer Fritz Zwicky to explain the lack of mass in the universe — visible galaxies "not enough" to celestial bodies behave as observed by astronomers. The title of this substance reflects its main feature: the dark matter in the gravitational interaction is involved and not involved in the electromagnetic (that is, it can not be observed directly), reports Lenta.ru.
Quantitatively, the universe is much more dark matter than "normal." Not long ago, astronomers have hypothesized that one of the types of objects consisting of the invisible substance, are dwarf satellite galaxies of large star clusters. It is believed that a "complete" galaxies like the Milky Way formed, attracting and absorbing its tiny neighbor. Follows from this assumption that major star formation must be surrounded by a large number of small satellites (in the case of the Milky Way is estimated to be the approximate number of 10,000). However, astronomers have actually found in the immediate vicinity of the galaxy, only about 30 "neighbors." Scientists have suggested that the remaining galaxies, for whatever reasons, were unable to form stars and are composed of dark matter.
The authors decided to find a new job this invisible companion of JVAS B1938 +666, consisting of the two galaxies, which are located on a straight line with each other, if you watch them from the Earth. This arrangement allows the use of gravitational lensing technique, or lens Einstein. Gravity of massive objects like galaxies deviate path of light coming from more distant objects, and parameters of the deviation depends on the mass of the deflecting the "lens." Observing with the Keck II telescope in Hawaii system JVAS B1938 +666, astronomers found that the system rejects the light path is not, as the theory predicts. Accordingly, the researchers concluded that the existence of a system of satellites of dark matter.
This is the second galaxy, consisting of unobservable substance, known in the art. The first one was 18 times as massive as the current one, and it was too big to be a satellite galaxy.