An international team of scientists, led by Dr. Themiya Nanayakkara from the Swinburne University of Technology, has discovered a massive spiral disk galaxy in the early universe, three times larger than similar galaxies at the same epoch. This finding challenges existing models of early formation and suggests that dense environments may be crucial for the creation of giant galaxies.
The discovery was made using data from the new James Webb Space Telescope (JWST) and other telescope observations targeted towards a specific region of the sky. The galaxy, dubbed the “Big Wheel,” is seen as it was 11 billion years ago, or 2 billion years after the Big Bang. Its optical radius is approximately 10 kpc, making it significantly larger than predicted by current cosmological simulations.
Further analysis revealed that the galaxy contains a disk rotating at around 300 km/s, with kinematics confirmed by the NIRSpec data. This makes the “Big Wheel” one of the largest kinematically confirmed disks found at similar early epochs.
The discovery provides new insights into the formation of giant galaxies in dense environments. According to Dr. Nanayakkara, these conditions may require non-destructive galaxy mergers or gas inflows that carry angular momentum co-rotating with the disk. This study paves the way for further research into this under-explored territory and could lead to a better understanding of early phases of galaxy formation.
The findings were published in Nature Astronomy and provide an exciting opportunity to study giant disks in the early universe, which remains relatively unexplored.
Source: https://phys.org/news/2025-03-large-disk-galaxy-early-universe.html