(ORDO NEWS) — A colossal shock wave, generated by the first stages of a collision between some of the most massive structures in the universe, has just been seen and photographed for the first time.
The detector was found in the galaxy. the Abell 98 cluster, which is a large structure consisting of three smaller subclusters of galaxies located more than 1.2 billion light-years away from the solar system.
There, a huge filament of gas contains a huge shock wave along the axis of the merger, which is theoretically predicted as the first “contact” between two subclusters of galaxies as they begin to merge.
“With this discovery, we have caught two subclusters of the cluster galaxy at a critical early epoch in the merger process, with a strong push in between providing the missing link for the formation of the most massive structures in our universe,” said physicist and astronomer Arnab Sarkar of the University of Kentucky.
The Universe is constantly in the process of interaction and self-organization. They are not isolated entities drifting through space, gravity is everywhere and the constant attraction and interaction results in clusters, superclusters, megaclusters and filaments dancing around each other and forming larger and larger structures.
These interactions, of course, do not occur on any time scales remotely close to human, but by observing clusters at different stages of merger, astronomers can reconstruct how these collisions occur.
In clusters of galaxies, as you can imagine, the gravitational environment is quite intense, and subclusters merge to form larger structures within the overall cluster.
In 2014, astronomers noticed that two subclusters within Abell 98, named A98N and A98S, appeared to be merging, as evidenced by b Accuracy and temperature signatures in A98N are consistent with the merger shock between them.
Sarkar and his team, who presented their results at the 240th meeting of the American Astronomical Society, took a closer look at the region between the two subclusters using the orbiting Chandra X-ray Observatory. There they found what they call “ultimate evidence” of the impact edge south of A98N.
This, they say, is a big deal. While inter-cluster and intra-cluster mergers should be fairly frequent (because the universe is full of galaxy clusters), early-stage mergers are quite rare. We see a lot in the later stages, including the shock waves generated by these extreme interactions, but very little as the clusters get closer.
Perhaps this is because they are harder to detect, but the discovery made Sarkar and his colleagues able to inform future searches by providing some information on what to look for.
And, of course, it fills in some important gaps in our understanding of how cluster mergers occur and evolve. This means that we will be able to better predict the evolution of galaxy clusters.
“This result is important because different computer simulations tell us different things about what we should observe early in the merger of galaxy clusters,” Sarkar said. “Here we have a picture of what this process actually looks like, and it can be used to inform our theoretical models.”
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