This extraordinary finding changes our understanding of how galaxies form and evolve.
Early galaxies are usually expected to be chaotic and irregular in appearance. However, this one, called REBELS-25, has amazed astronomers with its smooth and well-organized structure. With the help of the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA), scientists were able to capture the intricate details of this galaxy, revealing features such as spiral arms and a central elongated bar - characteristics usually associated with mature galaxies like our Milky Way.
The discovery is unexpected because current models of galaxy formation suggest that such well-ordered structures evolve over billions of years. Jacqueline Hodge, an astronomer at Leiden University and co-author of the study, commented, "We usually assume that the first galaxies will look small and chaotic, but REBELS-25 belies this expectation with its neatly organised shape."
Recent research has revealed compelling evidence that REBELS-25 is a rapidly rotating disk galaxy that existed only 700 million years after the Big Bang. This discovery identifies it as the earliest known galaxy with characteristics similar to our Milky Way, making it the most distant of its kind ever observed.
What makes the discovery even more puzzling is that REBELS-25 formed when the Universe was only 5% of its current age. Despite being so ancient, it is a mirror image of the Milky Way, which is thought to have evolved over 13.6 billion years. This raises profound questions about how quickly galaxies can evolve into the structured, rotation-dominated forms we observe today.
"To observe such an ancient galaxy already showing features similar to our Milky Way is a game-changer. It suggests that galaxies in the early Universe may have reached a level of maturity much faster than we ever imagined," said lead researcher Lucy Rowland, a PhD student at Leiden University.
But this discovery is just the beginning. The team now looks forward to further observations, especially with NASA's James Webb Space Telescope, which could provide even more detailed information about this ancient galaxy. It could challenge long-held theories about how galaxies form and lead astronomers to rethink how galaxies like the Milky Way came to be.
