On December 31, 2020, astronomers discovered a huge cluster of galaxies called RM J130558.9+263048.4; This date, combined with the galaxies' bubble-like appearance and superheated gas, inspired astronomers to name the object the Champagne Cluster. The new composite image of the cluster contains X-ray images from NASA's Chandra X-ray Observatory and optical data from Legacy Surveys.
The champagne cluster appears here as a large collection of bright white lights, each representing a different galaxy. A neon purple cloud stretches across the cluster's crowded core. Many of the more than one hundred galaxies in the cluster are divided into two clusters of galaxies above and below the center. Some of them are surrounded by a faint glowing haze, and a few stars in the foreground twinkle with diffraction spikes. Some of the smaller galaxies are blue, orange or red, and some appear more elongated than round, suggesting spiral shapes when viewed edge-on. A neon purple cloud is in the center of the image, surrounding the densest part of the cluster. This cloud, which extends vertically throughout the cluster, is the multimillion-degree gas observed by Chandra. The two observed galaxy clusters and the spread of superheated gas indicate that the Champagne Cluster is actually two clusters in the process of colliding. Image credit: NASA/CXC/UCDavis/Bouhrik etc.. / Legacy Survey / DECaLS / BASS / MzLS / SAO / P. Edmonds / L. Frattare.
In the new study, UC Davis astronomer Faik Bukhrik and colleagues used NASA's Chandra X-ray Observatory and ESA's XMM-Newton Observatory to observe the Champagne Cluster.
They also analyzed data collected by the DEIMOS Multi-Object Spectrograph at the W. M. Keck Observatory.
“The new composite image shows that the Champagne Cluster is actually two clusters of galaxies in the process of merging into an even larger cluster,” the astronomers said in a statement.
“Million-degree gas in galaxy clusters typically takes on a roughly circular or moderately oval shape in images, but in the Champagne cluster it is more widespread from top to bottom, indicating the presence of two colliding clusters.”
“Two clusters of individual galaxies that make up the colliding clusters can be seen above and below the center.”
“The hot gas exceeds the total mass of all the more than one hundred individual galaxies in the newly forming cluster.”
“The clusters also contain even larger amounts of invisible dark matter, the mysterious substance that permeates the universe.”
The Champagne Cluster is a member of a rare class of merging clusters that includes the famous Bullet Cluster, where the hot gas in each cluster has collided and slowed down, and there is a clear separation between the hot gas and the most massive galaxy in each cluster.
By comparing the data with computer modeling, the researchers came up with two possibilities for the history of the Champagne cluster.
First, these two clusters already collided with each other more than two billion years ago.
After the collision, the two clusters moved outward and were then pulled towards each other by gravity, and are now heading for a second collision.
Another idea is that one collision occurred about 400 million years ago, and after that collision the two clusters are now moving away from each other.
“Further studies of the Champagne Cluster could potentially show us how dark matter reacts to a high-velocity collision,” the scientists said.
Their paper was published in July 2025 in the magazine Astrophysical Journal.
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Faik Bukhrik etc.. 2025. Discovery and multi-wavelength analysis of a new dissociative merger of galaxy clusters: the Champagne cluster. APJ 988, 166; two: 10.3847/1538-4357/ade67c
