What is a fossil group?
The
fossil group is a galactic system in which some or all component galaxies have merged and created a single elliptical galaxy. This body has the weight and X -ray luminosity comparable to the sum of its components and is surrounded by a cloud of hot gas, which extends several galactic radii. Which system members who are not absorbed are usually far from and much smaller than the dominant member. It has been proposed that these systems have been formed in a very distant past and represent the final phase of evolution for the galactic group, hence the term "fossil".
Most galaxies, including the Milky Way, are part of the local group. In the most compact groups, the galaxies are almost enough to design that gravity will bring their possible merger into a single body focused in the halo of dark matter. This is a matter that does not radiate or reflect radiation, but can be detected by its gravitational effects. The presence of dark matter is derived from large clouds PLYNU emitting the húry X -ray radiation that usually surrounds these systems. It is assumed that such a process is formed by a fossil group over several billion years.
observation of galactic groups that seem to be in the process of creating a fossil group. These have strengthened the idea that this is a common result for systems of some density and the only method of creating fossil groups. However, further research has shown that evidence of fossil creation is less densely populated. In addition, massive fossil groups were examined that could not result from common dynamic friction models in the famous life of the universe.
The largest known fossil group was studied using XMM-New and Chandra X-ray cosmic observatory and chandra and ground-based telescopes. Its elliptical galaxy is 500 billion times light than the sun, a melonight of more than 300 trillion solar masses and sits in Halo Super-ZaA hot gas with a diameter of three million light -years. Depending on the received view of the formation of a fossil group, the structure of this size should not be available at the time.
was designed an alternative theory of formation, where the effects of dynamic friction acting on the bodies moving in circular orbital pathways at the center of the mass are replaced by an asymmetric model. If the weight is pulled towards the center along the fiber or fiber galactic structures, the known forces may be responsible for the formation at a much faster pace. The similarities between elliptical galaxies of fossil groups and clear galaxies in large clusters indicate another formative process. The final process of creating fossil groups could be the initial phase of formation for groups of clusters.