NASA’s James Webb Space Telescope has revealed groundbreaking new images showing that many early galaxies had odd, elongated shapes rarely seen in the local universe today. These early galaxies took the form of thin disks, squiggles, massive blobs, and even some described as resembling “pool noodles” or “surfboards.”
Webb Solves Mystery of Ancient Starlight
For decades, astronomers have grappled to explain why distant, early galaxies produce such intense ultraviolet light. Models of the early universe indicated that young galaxies should not have enough stars and black holes at their centers to generate the amount of UV light detected from the distant past.
But as reported in NASA’s news release, Webb’s incredible sensitivity and imaging capabilities have now solved this mystery. Webb observed a galaxy merger occurring when the universe was only 10% of its current age. In the violence of the merger, huge amounts of gas and dust are compressed, triggering a rapid formation of new stars. The UV light comes from these firestorms of new star birth, rather than pre-existing stars or black holes.
“These mergers trigger bursts of star formation that produce a lot of very hot, very blue stars,” said Marcia Rieke of the University of Arizona, lead author of the Nature studyrevealing these findings. “The hottest blue stars don’t live long and burn out early, which might explain why these ancient galaxies pop in and out of view. Many of these ancient mergers may have produced brief hyper starbursts.”
Odd Early Galaxy Shapes Point to Turbulent Formation
Another remarkable finding reported this week indicates that while present-day galaxies tend to have spherical or disk-like shapes, early galaxies had much more irregular forms. Based on Webb’s first fully-commissioned images, astronomers describe galaxies at cosmic dawn resembling “just about everything in the Hubble Deep Field and more.”
Some appear as massive blobs or elongated ellipsoids. Others are long strands or “train wrecks” caught in the midst of collision. There are also early galactic disks, but they do not have the orderly rotation that defines our Milky Way. Instead, they are dynamically hot and turbulent.
“There are shapes ranging from discs to blobs to things that look like bread sticks,” said astronomer Joel Leja. “We don’t really see bread-stick galaxies today. We see a lot of spiral galaxies, we see elliptical galaxies, but we don’t see things that look like noodles coming out of a mess of stars.”
The diversity of shapes supports the idea that early galaxies grew chaotically through violent collisions and mergers. Gravity and turbulence molded the stars and gas into new structures. Only later did galaxies cool down enough to form the orderly shapes we observe closer by.
Galaxy Mergers Unveil Earlier Mystery of Hydrogen Emission
Webb also solved a second longstanding mystery this week concerning hydrogen emission from the early universe. Researchers using Webb data found that ancient galaxy mergers can explain this emission, which did not match predictions.
“The dense gas in these mergers fuels very rapid black hole growth as well as bursts of star formation,” explained NASA Astrophysicist Jane Rigby. When the first generations of stars end their lives, they produce ionizing radiation that interacts with the gas. This produces the hydrogen signature that Webb surprisingly detected, even exceeding theoretical models.
So in visible light, Webb spotted highly irregular galaxies indicative of mergers. And in infrared light, it picked up excess ionizing radiation – confirming that violent mergers triggered the emission through bursts of star formation and black hole activity.
“It’s remarkable that Webb was able to resolve and pinpoint multiple galaxies undergoing multiple mergers at this early epoch,” said astronomer Ivo Labbe. “This is exactly what we hoped to accomplish with Webb.”
|James Webb Space Telescope
Path Forward: Next Steps for Webb and Early Universe Research
With these breakthroughs, Webb has exceeded expectations for its first year of science operations. But this is only the beginning for NASA’s flagship observatory. What other revelations lie ahead as researchers continue analyzing Webb data on the early universe?
Upcoming research will provide new details on additional discoveries briefly reported in recent days:
- Further analysis of merger environments and their star formation rates
- The relationship between star formation and black hole growth from galaxy interactions
- Better statistics on the diversity of early galaxy types, shapes and colors
- Insights into dwarf galaxies and less massive stellar systems at cosmic dawn
Webb’s instruments were designed to peer deep into two areas: the atmospheres of exoplanets, and the earliest eras of cosmic history. With its first year focused on the early universe, Webb is now meeting its aspirations and more. The pool noodle galaxies will undoubtedly become iconic of this mission that offers humanity an unprecedented glimpse across space and back in time.
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