For the first time, the well-known colossal shock wave generated by the first stages of a collision between some of the most massive structures in the Universe has been seen and imaged.
This wave was scrutinized in the galaxy cluster Abell 98, a large structure of three smaller sub-clusters of galaxies located more than 1.2 billion light-years from the Solar System.
In there, it was uncovered that a massive filament of gas comprises the enormous shock along the merger axis that has been theoretically foreseen to be the first ‘contact’ between two sub-clusters of galaxies as they start to merge.
A physicist and astronomer, Arnab Sarkar of the University of Kentucky, said, “With this discovery, we caught two sub-clusters of a galaxy cluster in a crucial early epoch of the merging process, with a strong shock between them, providing a missing link to the formation of the most massive structures in our Universe.”
It is a well-known fact that The Universe is frequently interacting with and modifying itself. Galaxies aren’t isolated entities drifting through space; gravity is universal, and the constant push-pull and interplay results in clusters and superclusters and mega clusters and filaments, parading around each other and forming larger and ever more significant structures.
These interactions don’t indicate anything remotely addressing human timescales, but by observing clusters at different stages of merging, astronomers can reconstruct how these clashes occur.
Within galaxies, the gravitational environment is pretty severe, with sub-clusters integrating to form larger structures within the all-around cluster.
It was noted in 2014 by astronomers that two sub-clusters within Abell 98 – named A98N and A98S – appeared to be merging, as evidenced by brightness and temperature signatures in A98N consistent with a merger shock between the two.
Sarkar’s statement reads, “This result is important because diﬀerent computer simulations seem to be telling us diﬀerent things about what we should observe early on in a galaxy cluster merger. Here, we have a picture of what this process actually looks like, and that can be used to inform our theoretical models.”
These groundbreaking results were presented at the 240th meeting of the American Astronomical Society. Describes the findings have been submitted to The Astrophysical Journal.