Astronomers study the structure of an extremely massive cluster of galaxies

New observations conducted by an international team of astronomers provide important information about the extremely massive cluster of galaxies called PLCK G287.0 + 32.9. These results help to better understand the structure of this cluster and the distribution of mass in it.

The accumulation of galaxies PLCK G287.0 + 32.9 was first discovered with the help of the European Space Agency Planck (Planck) satellite in 2011. The first observations showed that it is an extremely massive cluster of galaxies lying at a redshift of 0.39 and having a mass approximately 1.57 quadrillion (1570 trillion) solar masses. Subsequent observations revealed a pair of giant radio relics in a cluster of galaxies PLCK G287.0 + 32.9.

Radio-relays are scattered, elongated sources of radio signals of synchrotron origin. They are observed in the form of spectacular single or double symmetrical arcs on the periphery of galaxy clusters. It is believed that these sources are formed as a result of acceleration and re-acceleration of matter in shock waves that occur in collisions. Therefore, in the case of a cluster of galaxies PLCK G287.0 + 32.9, radio-relics confirm that this cluster is in the process of formation from several smaller aggregating clusters of galaxies.

However, the asymmetry of the radio-relics of the PLCK G287.0 + 32.9 cluster indicates a complex fusion configuration. To clarify the details of this configuration in a new study, astronomers led by Kyle Finner of the University of Yonsei, Republic of Korea, analyzed the distribution of dark matter in the cluster of galaxies PLCK G287.0 + 32.9 using the weak-lensing analysis method, , using for observation the 8.2-meter Subaru telescope located in Hawaii, and NASA’s Hubble Space Telescope (Hubble).

As a result of observations, Finner and colleagues obtained data that allowed us to correct the estimate of the mass of this cluster, which according to these data amounted to 2.04 quadrillion solar masses. The structure of the cluster of galaxies PLCK G287.0 + 32.9 includes the main cluster of galaxies and the three substructures associated with it, which account for about 10 percent of the mass. The fifth observed in the PLKK cluster G287.0 + 32.9 substructure is much less massive compared to the others, and can not be considered as a full cluster of galaxies, the authors indicate.

Researchers hope that in the future the Hubble space telescope will provide new, even more detailed information about the structure of the galaxy cluster of PLCK G287.0 + 32.9.

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