Galaxy Cluster Environment Not Determined By Mass Alone, Scientists Examine Connection
For the first time, researchers found that the link between galaxy clusters and their surrounding dark matter is not categorized solely by the clusters' mass, but by their formation history, according to a study.
The growth of galaxy clusters has been debated between the accumulation of dark matter by gravity and the increasing expansion of the universe due to dark energy. Galaxy clusters offer researchers an opportunity to study the building blocks of the early universe.
"I am thrilled that we have finally found clear evidence of the connection between the internal structure of clusters and surrounding dark matter environment," Hironao Miyatake, coauthor of the study, said in a news release. "I am also excited that our findings will give insights on many aspects of the universe, such as large scale structure, dark matter and dark energy, and inflation physics."
The researchers divided about 9000 galaxy clusters from the Sloan Digital Sky Survey DR8 galaxy catalog into two categories based on the spatial distribution of galaxies in each of the clusters. With the use of gravitational lensing, the researchers confirmed that both sample had similar masses, however, the distribution of clusters were quite different. They found that galaxy clusters that were crowded in the center were less clumpy compared to clusters where galaxies were more spread out. The researchers concluded that the difference in distribution is a result of the diverse dark matter environment in which they are formed.
The researchers' findings reveal that the link between a galaxy cluster and surrounding dark matter is not categorized by the mass of clusters alone, but by their formation history as well.
The findings of this study were published in Physical Review Letters.
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