Astronomers using the James Webb Space Telescope have discovered an unexpected feature in a distant, early galaxy. Despite forming when the universe was still very young, this galaxy shows no signs of rotation.
Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis, and lead author of the study published May 4, explained that such behavior is typically only seen in very large, mature galaxies much closer to Earth. natural astronomy.
“It didn’t show any particular evidence of rotation, but it was surprising and very interesting,” Forrest said.
Why galaxies are expected to rotate
Current models suggest that galaxies begin to rotate as they form. The inward flowing gas and the gravitational pull create angular momentum that sets these systems into motion.
Over billions of years, galaxies can collide and merge, especially in dense galaxy clusters. These repeated interactions can increase rotation or cancel rotation. As a result, some nearby galaxies show little overall rotation, instead showing stars moving in random directions.
This change is thought to take a very long time, so it’s surprising to see it in galaxy XMM-VID1-2075, when the universe was less than 2 billion years old.
Giant galaxies that formed early
As part of the MAGAZ3NE (z>3 NEar-Infrared Giant Ancient Galaxies) study, Forrest and his colleagues had already studied this galaxy using the WM Keck Observatory in Hawaii.
“Previous MAGAZ3NE observations have confirmed that this galaxy is one of the most massive galaxies in the early universe, and that it already has several times as many stars as the Milky Way. We also confirmed that no new stars are forming, making it a promising target for follow-up observations,” Forrest said.
Webb telescope reveals internal motion
The research team used the James Webb Space Telescope to examine XMM-VID1-2075 alongside two other galaxies from the same era. This allows them to track how material moves within each system.
“This kind of study has been done a lot with nearby galaxies because they are closer and larger, so you can do this kind of study from the ground. But it’s very difficult to do that with high-redshift galaxies because they look much smaller in the sky,” Forrest said. “(The James Webb Space Telescope) is really pushing the frontiers of this kind of research.”
Of the three galaxies, one clearly rotates, another exhibits an irregular structure, and the third exhibits no rotation but strong random motion of its stars.
“This is consistent with some of the most massive galaxies in the local universe, so it was a bit of a surprise that it was discovered so early,” Forrest said.
What stops galaxies from rotating?
Researchers are now trying to understand how this galaxy rapidly transformed into what scientists call a “slowly rotating body.”
One possible explanation is a single dramatic conflict rather than a long history of multiple mergers. If two galaxies rotating in roughly opposite directions collide, their motions can cancel out.
“We see that this particular galaxy is emitting a lot of extra light sideways, which suggests that some other object could come in and interact with this system and change its dynamics,” Forrest said.
Exploring more spinless galaxies
The research team continues to search for similar galaxies in the early universe. By comparing observations with computer simulations, scientists can test whether current theories about galaxy formation hold up.
“There are some simulations that predict that very few of these non-rotating galaxies existed in the very early days of the universe, but they expect them to be very rare. So this is one way that we can test these simulations to really get a sense of how common they are, and that can give us information about whether our theory about this evolution is correct,” Forrest said.
Other co-authors of this paper include: Brian C. Lemaux, University of California, Davis, and Gemini Observatory, Hawaii. Adam Mazin and Adit H. Edwards, York University, Toronto. Danilo Marchesini, Richard Pan, Nehil Ozden, Tufts University; Jacqueline Antwi-Danso, University of Toronto. Wenjun Zhang, University of California, Riverside; MC Cooper and Stephanie M. Urbano Stawinski, University of California, Irvine. Percy Gomez, W. M. Keck Observatory, Kamuela, Hawaii. Lucas Kimmig and Rhea-Silvia Remus, Ludwig-Maximilians-University Munich, Germany. Ian McConachie, University of Wisconsin-Madison; Alison Noble, Arizona State University. Gillian Wilson and ME With of the University of California, Merced;
This research was supported by grants from NASA, the Space Telescope Science Institute, and the National Science Foundation.
