Coma cluster – evolution and dark matter
Australian researchers have shown for the first time that the capture and storage of Coma cluster have so much dark matter, at least 100 times higher than the ordinary matter, which has protected the visible matter, about 7 billion years ago, by the gravitational effects due to the cluster. And what emerges from a series of sophisticated numerical simulations, the results were published in Monthly Notices.
According to a study by Australian researchers, galaxies belonging storage of Coma, one of the larger structures that are known to about 300 million light years from Earth in which thousands of galaxies are held together by gravity located, may contain an amount of dark matter at least 100 times higher than the visible matter. To reach this conclusion, the authors used sophisticated computer simulations whose results are published in Monthly Notices of the Royal Astronomical Society.
Credit: Cameron Yozin, ICRAR/UWA
This artist’s impression of the ‘quenching’ process shows how a normal blue (star-forming) galaxy lost its gas while falling into the Coma Cluster very early on in its formation.
“Our work shows for the first time that galaxies have been captured from store about seven billion years ago, which suggests, according to our current theories of galactic evolution, they must have so much dark matter, at least 100 times higher than the ordinary matter. Dark matter acts as a sort of ‘shield’ protecting the visible matter by gravitational effects due to storage, “says Cameron Yozin doctoral student at the University of Western Australia and the International Centre for Radio Astronomy Research (ICRAR) and author of the study. “The galaxies that we reviewed have approximately the same size as the Milky Way, but contain only one percent of stars.”
Moreover, according to the authors, star formation appears to have halted the moment the galaxies were initially captured from storage between about 7-10 billion years ago. Since then the galaxies are like “death” and so astronomers have coined the term “missed galaxies”. The end of the star formation process is known as “quenching”, i.e. extinction. “Originally, the galaxies are formed when huge clouds of hydrogen gas collapse and turn into stars. But if the gas is removed, the Galaxy cannot evolve”, says Yozin. “One of the ways by which this occurs is the gravitational pull of the galaxy as part of the cluster. Indeed, the enormous gravity of storage attracts the galaxy and its gas is ejected or better ‘stolen’ from the hot gas in the cluster present. For the first time, my simulations have shown that the extinction of these galaxies would have caused the same from store about seven billion years ago. However, during this process of gravitational pull, the galaxies have not been completely destroyed due to the existence of giant envelopes of dark matter that protected the stars. ”
This study was motivated by the recent discovery of this type of galaxies in the cluster of Coma by a group of American and Canadian researchers led by Pieter van Dokkum of Yale University. With the data provided by this group, which were published last year, Yozin was able to create a series of numerical simulations to build models in an attempt to describe how they have evolved galaxies in those structures that we admire today.