(ORDO NEWS) — Scientists at the Federal Polytechnic School of Lausanne (Switzerland) have found that the evolution of galaxies is determined by the cosmic web – threads of dark matter in intergalactic space, along which ordinary (baryonic) matter is concentrated.
A preprint article published in the arXiv repository reports that the filaments quench the star formation of galaxies that fall into galaxy clusters.
The researchers studied the space surrounding the Virgo Cluster, which contains about 1,500 galaxies and lies 65 million light-years from the Milky Way.
The properties of galaxies located in a region 12 times larger than the radius of the main cluster were analyzed. The sample covered about seven thousand galaxies, including 250 large enough to be able to accurately estimate the content of gas, especially the amount of cold dense atomic hydrogen from which stars are formed.
It turned out that such characteristics of galaxies as shape, star formation rate, gas content, as well as age and metal content in stars change as clusters evolve, when galaxies move from more isolated positions in the direction of filaments and eventually into clusters. This explains the decrease in the rate of formation of new stars when approaching clusters.
Thus, the filaments play the role of a transitional medium, where galaxies are modified before falling into clusters. In this environment, star formation slows down or stops, the amount of atomic and molecular hydrogen decreases, which indicates that galaxies are coming to the end of their active life.
There is a pattern: galaxies in which stars are not produced make up 20 percent of the sample of isolated galaxies, but in the cluster itself, their proportion grows to 80 percent.
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