REBELS-25 is a galaxy similar to the Milky Way discovered in the early universe, which breaks with the traditional model with its ordered structure, suggesting that galaxies are evolving rapidly. Astronomers have discovered the most distant Milky Way-like galaxy ever observed, named REBELS-25.
This disk galaxy looks as orderly as the galaxies we see today, but it dates back to when the universe was only 700 million years old. This discovery challenges the dominant theories about galaxy formation, which suggest that such early galaxies should exhibit a more chaotic structure. The Atacama Large Millimeter/Submillimeter Array (ALMA), operated in collaboration with the European Southern Observatory (ESO), revealed the rotation and structure of REBELS-25.
This image shows the REBELS-25 galaxy observed by the Atacama Large Millimeter/Submillimeter Array (ALMA), superimposed on infrared images of other stars and galaxies. This infrared image was taken by the Visible and Infrared Survey Telescope (VISTA) at the European Southern Observatory. In a recent study, researchers found evidence that REBELS-25 is a strongly rotating disk galaxy that existed just 700 million years after the Big Bang. This makes it the most distant and earliest known galaxy ever discovered. Source: ALMA (ESO/NAOJ/NRAO)/L. Rowland et al./ESO/J. Dunlop et al. Dunlop et al： CASU， CALET
"The galaxies we see today are a long way from the chaotic, clumpy galaxies that astronomers typically observed in the early universe." Jacqueline Hodge, an astronomer at Leiden University in the Netherlands and co-author of the study, said: "Based on our understanding of galaxy formation, we expect most early galaxies to be small and look messy. "
These haphazard early galaxies fused with each other and then evolved into smoother shapes at an incredibly slow pace. Current theories suggest that for a galaxy to become as orderly as our galaxy – a rotating disk with a neat structure such as spiral arms – it would have to evolve over billions of years. However, the results of the REBELS-25 probe present a challenge to this time scale.
This image of the REBELS-25 galaxy was taken by the Atacama Large Millimeter/Submillimeter Array (ALMA), an international facility co-owned by the European Southern Observatory (ESO). It shows the distribution of cold gas in galaxies and shows an elongated strip structure in the center of the galaxy. (Image: ALMA (ESO/NAOJ/NRAO)/L. Rowland et al.
In the study, published today (7 October) in the Monthly Notices of the Royal Astronomical Society, astronomers discovered that REBELS-25 is the most distant strong rotating disk galaxy ever discovered. The light emitted from this galaxy was emitted when the universe was only 700 million years old, only 5% of the current age of the universe (13.8 billion years), so the orderly rotation of REBELS-25 was beyond our expectations.
Lucie Rowland, a PhD student at Leiden University and lead author of the study, said: "Seeing a galaxy so similar to ours with a strong rotational dominance challenges our understanding of how galaxies in the early universe quickly evolved into ordered galaxies in the universe today. "
This image shows the movement of cold gas in the REBELS-25 galaxy as observed by the Atacama Large Millimeter/Submillimeter Array (ALMA). Blue means moving towards the Earth, red means moving away from the Earth, and darker the color means faster the movement. In this case, the red-blue dividing line of the image clearly shows that the object is rotating, making REBELS-25 the most distant rotating disk galaxy ever discovered. Source: ALMA (ESO/NAOJ/NRAO)/L. Rowland et al.
REBELS-25 was first discovered during previous observations by the same research team, also through ALMA in the Atacama Desert in Chile. At the time, it was an exciting discovery, showing signs of rotation, but the resolution of the data was not fine enough to be determined. In order to correctly discern the structure and motion of this galaxy, the team conducted follow-up observations with higher-resolution ALMA, which confirmed its record-breaking nature.
Renske Smit, a researcher at Liverpool John Moores University in United Kingdom and one of the study's co-authors, said: "ALMA is currently the only telescope with the sensitivity and resolution to achieve this. "
Surprisingly, the data also hint at more developed features similar to those of the Milky Way, such as a central elongated strip structure and even spiral arms, although more observations are needed to confirm this. "Finding more evidence of evolutionary structures would be an exciting discovery, as it would be the most distant galaxy with such structures observed to date," Rowland said. "
Future observations of REBELS-25, as well as the discovery of other early rotating galaxies, have the potential to change our understanding of early galaxy formation and the evolution of the universe as a whole.
This image shows regions of stars and galaxies captured by a VISTA NIR camera. Among them, REBELS-25 is the most distant spinning disk galaxy ever discovered. VISTA is a visible and infrared survey telescope of the European Southern Observatory, located in the Atacama Desert in Chile. Image credit: ESO/J. Dunlop et al: CASU, CALET
编译自/SciTechDaily