Astronomers Detect Extremely Rare Sextuple Galaxy Merger

• Astronomers have identified an extremely rare "sextuple" galaxy merger at the heart of a galaxy cluster, where six massive galaxies are colliding to form a single supermassive galaxy.
• The discovery was made using data from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys.
• Researchers estimate the resulting galaxy will have a mass of approximately 1.16x10^12 solar masses once the merger completes in 800 million to 1.9 billion years.

Discovery and Rarity

• Located in a cluster identified via DESI data, this specific system—designated WHY J0501+01—is exceptionally rare.
• Out of 52,803 surveyed galaxy clusters, this is the only one found to contain more than four merging galaxies.
• For context, the sample set contained 2,233 binary mergers, while quadruple mergers are limited to only 12 known examples.

Physical Dynamics

• The cluster features a 310-kiloparsec shroud of Intracluster Light (ICL), representing a "fog" of stars stripped from the host galaxies during the violent collision.
• Five of the six involved galaxies possess masses exceeding 10^11 solar masses (roughly 100 billion stars each).
• Observations from the Einstein Probe’s Follow-up X-ray Telescope (EP-FXT) revealed "sloshing" in the surrounding ultra-hot plasma and a distinct plasma "tail," confirming the system is highly active and "unrelaxed."

Scientific Significance

• By capturing this rare event, researchers gain insights into the formation processes of the universe's largest galaxies.
• Studying these extreme mergers provides a "real-time" look at galactic evolution, which helps improve theoretical models of how clusters develop over cosmic time.