Deep X-ray Observation of Abell 2029 – Researchers have uncovered evidence of ancient cosmic collisions within this galaxy cluster, recognized as the most serene in the universe, which features a colossal spiral of superheated gas stretching over two million light-years.
This composite image integrates both original and subtracted X-ray data from Abell 2029’s Chandra deep observations. Image credit: NASA / CXC / CfA / Watson et al. / Panstars/SAO/N.Walk/P.Edmonds.
“Galaxy clusters are the largest gravitationally bound structures in the universe,” stated Boston University astronomer Courtney Watson and her colleagues.
“These clusters contain hundreds or even thousands of galaxies, along with invisible dark matter and significant amounts of gas that fill the spaces between galaxies.”
The gas, heated to millions of degrees, emits X-ray light, allowing astronomers to study it effectively.
Utilizing NASA’s Chandra X-ray Observatory, astronomers have conducted the deepest X-ray observations of Abell 2029, a galaxy cluster approximately one billion light-years away in the constellation Virgo.
New data indicate that this galaxy cluster is continuing to settle after a violent collision with a smaller cluster around 4 billion years ago.
“The spiral shape of the hot gas likely formed when the gravitational forces from the cluster collision caused the gas to be pushed sideways, similar to how wine moves within a glass,” the researchers explained.
The sloshing spiral of Abell 2029 is one of the longest ever recorded, extending roughly two million light-years from its center.
“We have uncovered significant evidence of past collisions that have not been previously seen together in a cluster, enabling us to trace the cluster’s collision history with unprecedented detail.”
“For instance, we observe signs that the collision dispersed cold gas across a broad area.”
“The remnants of superheated gas from the collision may also produce shock waves akin to sonic booms generated by supersonic aircraft.”
“Additionally, the hot gas displays a ‘bay’ feature, likely resulting from the overlap between the outer section of the vortex and the materials stripped from the smaller clusters as they traversed the larger clusters.”
“We believe this indicates impact debris, although alternative explanations may exist.”
According to the researchers’ computer simulations, the smaller cluster’s mass was about one-tenth that of the larger cluster.
“The sloshing spiral emerged when a small star cluster initially passed through a larger one, pulling gas sideways,” the scientists noted.
“The gravity of the larger cluster then decelerated the smaller cluster, leading to a second collision.”
“This triggered the shockwave, creating a wake of material and forming a droplet field.”
To uncover these various features, the authors employed a specialized technique that analyzes how much the cluster’s hot gas deviates from a symmetrical shape.
“Most hot gases are symmetrical and roughly elliptical in shape.”
The team’s results were published in the Astrophysical Journal.
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Courtney B. Watson et al. 2026. Deep Chandra X-ray observations of A2029: Merger history of a relaxed and strong cool core cluster. APJ 996, 106; doi: 10.3847/1538-4357/ae2026
Source: www.sci.news
