An international team of astronomers reports the detection of a peculiar merger of two similar ring galaxies that morphologically resemble an owl’s face. The discovery of this galaxy merger, dubbed the “Cosmic Owl,” is presented in a research paper published June 11 on the arXiv preprint server.
Galaxy mergers play a crucial role in the evolution of galaxies. These events redistribute the gas around galaxies, impact the stellar kinematics, transform galaxy morphology, and eventually lead to effective stellar mass assembly.
Some galaxy mergers lead to the formation of collisional ring galaxies (CRGs), which are relatively rare as only a few hundred of them have been detected in the local universe. Rings in such galaxies are created when one galaxy passes directly through the disk of another in a nearly head-on collision, causing gas and stars to be shocked outward into a circular or near-circular pattern.
Now, a group of astronomers led by Mingyu Li of the Tsinghua University in Beijing, China, has identified what seems to be a unique galaxy merger of two collisional ring galaxies. The galaxy merger was serendipitously detected using such instruments as the James Webb Space Telescope (JWST), the Atacama Large Millimeter/submillimeter Array (ALMA) or the Very Large Array (VLA).
“Deep imaging and spectroscopy from JWST, ALMA, and VLA reveal a complex system of twin collisional ring galaxies, exhibiting a nearly identical morphology,” the researchers wrote in the paper.
The galaxy merger was detected at a redshift of 1.14. The collected images show that the Cosmic Owl consists of two interacting galaxies that have formed nearly identical collisional ring structures, each with a diameter of approximately 26,000 light years.
The astronomers noted that the symmetry of the rings of the Cosmic Owl suggests a head-on collision origin between two galaxies of similar mass and structure. They estimate that the stellar mass of the merging system is about 320 billion solar masses, while the black holes in the two galaxies have masses of around 67 and 26 million solar masses.
The images reveal that the compact core of each galaxy forms an eye of the Cosmic Owl, while a central region of intense star formation, enhanced by younger stellar populations and nebular emission, appears in blue, resembling a beak between them.
Furthermore, the study found that each of the merging galaxies hosts an active galactic nucleus (AGN) and that the northwestern “eye” has a bipolar radio jet. It appears that the jet extends to the beak region and induces additional shocks in the collision front between the two galaxies.
Summing up the results, the authors of the paper underlined the unique properties of the Cosmic Owl.
“The simultaneous occurrence of a head-on merger, twin ring formation, dual AGN activity, and a jet-triggered starburst offers a detailed snapshot of the mechanisms that assemble stellar mass and grow supermassive black holes in the early universe,” the researchers concluded.
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More information:
Mingyu Li et al, The Cosmic Owl: Twin Active Collisional Ring Galaxies with Starburst Merging Front at z=1.14, arXiv (2025). DOI: 10.48550/arxiv.2506.10058
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The Cosmic Owl: Astronomers discover a peculiar galaxy merger (2025, June 19)
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