Possible dark matter-deficient twins discovered in the Fornax Cluster
Phys.org • • science
Key Points:
- Astronomers have identified two galaxies, FCC 224 and FCC 240, in the Fornax Cluster that may belong to the rare class of dark-matter-deficient galaxies, similar to the previously known pair NGC 1052-DF2 and DF4.
- Both FCC 224 and FCC 240 exhibit extremely low velocity dispersions and host unusually bright globular clusters, with dynamical masses consistent with their stellar masses alone, indicating little to no dark matter presence.
- The galaxies share the same age of about 10 billion years, and their stars and clusters likely formed simultaneously during a brief, intense burst of star formation, supporting the "bullet-dwarf" collision scenario.
- Unlike the widely separated DF2 and DF4, FCC 224 and FCC 240 form a compact, bound pair moving slowly toward each other, suggesting possible variations in collision geometry or orbital energy affecting their formation.
- These findings imply that dark-matter-deficient galaxies may not be unique to a single group and that similar high-velocity collisions could produce such galaxies in different environments.