Astronomers have captured a breathtaking new image of an extremely rare event, that is, the capture of a group of galaxies by a larger cluster of galaxies.
Such an event could provide an alternative explanation for how such great structures have evolved in the Universe. The galaxy clusters can in fact also contain thousands of galaxies and most of the mass is due to ionized hot gas, which emits large amounts of energy in the X-band, or dark matter, the great obsession of cosmologists and astrophysicists.
Thanks to this discovery, it seems that one of the possible ways of accretion of the galactic clusters is the gravitational capture of other nearby galaxies. These are events that naturally last millions, perhaps billions of years. But of which we finally have a taste.
The image, taken from the Chandra space telescope, shows an incredible hot gas tail, over a million light years long, which spreads behind a small group of four galaxies, which in turn is heading towards the center of the Abell 2142 cluster. The tail gas has a temperature of several million degrees and its shape suggests that there are powerful magnetic fields at play that have a containment effect, at least in the initial part of the gas jet.
This study, published in Nature, was also attended by Tiziana Venturi, director of the Institute of Radioastronomy INAF of Bologna, who commented on the discovery:
This result is very important for our understanding of the formation and evolution of large structures, such as galaxy clusters. Here in Abell 2142 we are witnessing the “fall” of a group of galaxies in the main cluster, and the emission trail X traces this motion. Events of this type, hypothesized by the theories of formation of large structures, are very difficult to observe, and this gives rise to the relevance of the work.