James Webb unravels secrets of gigantic "Big Wheel" galaxy

Profound observations from the James Webb Space Telescope revealed a vast galaxy in the early universe. This cosmic giant, whose light traveled over 12 billion years to reach us, was named "Big Wheel" by researchers. Their discovery was published in the scientific journal Nature Astronomy.

This gigantic disk galaxy existed within the first two billion years after the Big Bang, forming when the universe was just 15 percent of its current age. This challenges what we know about how galaxies form.

What is a disk galaxy? It's a flat, rotating structure of stars, gas, and dust. Disk galaxies typically have distinct spiral arms extending outward from the dense central region. Our Milky Way is a disk galaxy characterized by beautiful spiral arms wrapping around its center.

Studying disk galaxies such as the Milky Way and the newly discovered "Big Wheel" helps us understand how galaxies form, grow, and evolve over billions of years. This research is significant because understanding galaxies similar to ours can provide deeper insights into the cosmic history of our galactic home.

Until now, researchers have believed that galactic disks form gradually over a long time, either through the smooth inflow of gas into galaxies from surrounding space or through mergers with smaller galaxies.

Rapid collisions between galaxies would typically disrupt delicate spiral structures, transforming them into more chaotic shapes. However, "Big Wheel" managed to quickly reach a surprisingly large size without losing its characteristic spiral shape. This challenges long-held theories about the growth of giant galaxies.

Detailed observations by the Webb Telescope show that "Big Wheel" is comparable in size and rotational speed to the most prominent "super-spiral" galaxies in the contemporary universe. It is three times larger than comparable galaxies from that era and is one of the most massive galaxies observed in the early cosmos. Interestingly, despite being extremely large, "Big Wheel" actively grows at a rate similar to other galaxies at the same cosmic age.

Researchers describe the "Big Wheel" as being located in an extraordinarily crowded region of space where galaxies are packed closely together, ten times denser than in typical areas of the universe. This dense environment likely provided the ideal conditions for the rapid growth of the galaxy. It likely experienced collisions that were gentle enough to allow the galaxy to maintain its spiral disk shape. Additionally, the gas inflow into the galaxy must have been well-aligned with its rotation, allowing the disk to grow rapidly without disturbances. This is an ideal combination.

The discovery of a galaxy like "Big Wheel" was improbable. According to current models of galaxy formation, we had less than a 2 percent chance of finding this in our study," scientists said in an interview with Science Alert. They added that their discovery was surprising, likely because we observed it in an exceptionally dense region, unlike typical cosmic environments.

Beyond its mysterious formation, the ultimate fate of the "Big Wheel" is another intriguing issue. Scientists predict that, given its dense environment, future collisions may significantly alter its structure, potentially transforming it into a galaxy comparable in mass to the largest observed in nearby clusters, such as Virgo.

"The discovery of 'Big Wheel' has unveiled another secret of the early universe, showing that our current models of galaxy evolution still require refinement," researchers said. With further observations and discoveries of massive, early galaxies like the "Big Wheel," astronomers can uncover more mysteries regarding how the universe built the structures we see today.