- This massive object was found 510 million years after the Big Bang, and was 10 times larger than other objects in the early universe.
- The observations were made using the James Webb Space Telescope, making it possible to see details of a galaxy at the edge of the observable universe.
- JWST also allowed us to detect how many young and older stars there are in the galaxy under study
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An international group of scientists has made detailed observations of the first galaxy merger ever observed. The massive object, examined with the James Webb Space Telescope, existed 510 million years after the Big Bang, or about 13 billion years ago.
“When we made these observations, this galaxy was 10 times larger than any other galaxy in the early universe,” says Dr Kit Boyett from the University of Melbourne, lead author of the study published in the journal Nature Astronomy. The publication includes 27 authors, coming from as many as 19 centres: Australia, Thailand, Italy, USA, Japan, Denmark and China.
Scientists confirm that thanks to the James Webb Space Telescope, ancient distant objects that were previously visible as single points are revealing their complex structure.
– It is amazing to see how the power of the James Webb Space Telescope allows us to see details of galaxies at the edge of the observable universe and thus travel back in time. This space observatory changes our understanding of the formation of early galaxies – says co-author of the discovery Prof. Michelle Trinity.
The new observations show a galaxy made up of several clusters of stars, with two large objects at the center and a long tail. Astronomers explain that this structure indicates the merging of two galaxies into one.
– The call is not over yet. We can know this because there are two objects. The long tail likely formed from material ejected from merging galaxies. When such a combination occurs, some of the material is usually eliminated. This tells us that we are dealing with a merger. Dr. Boyett says this is the most distant galaxy merger ever recorded.
New observations force scientists to revise current models
– Thanks to the James Webb Telescope, we see more objects in the young universe than we expected. In addition, these objects are more massive than we thought. The expert confirms that our cosmological models are not necessarily wrong, but our understanding of galaxy formation rates may be wrong because they are larger than we thought possible.
However, it was not only the size of the galaxies and the speed of their formation that surprised researchers. The James Webb Space Telescope also revealed surprises about the number of stars themselves.
– When we compared spectroscopy with images, we found two different things. The images indicated the presence of a number of young stars, and the spectroscopic data indicated somewhat older stars. Both observations are true because we have two groups of stars, not one, says Dr. Boyett.
“There were a number of old stars here a long time ago, and we think the merger of galaxies gave rise to new stars. We now see young stars against the background of old stars,” the researcher adds.
Previous observations showed young stars, but this was likely because they are brighter and easier to spot. However, the James Webb Space Telescope allows us to distinguish between stars of different brightness. “It's not unusual. We know that throughout the history of the universe there have been peaks in the production of new stars for various reasons, giving rise to many star clusters. However, this is the first time it has been seen from this distance,” says Dr. Boyett.
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