Image Courtesy: ScienceDaily
Astronomers using the James Webb Space Telescope have discovered a massive galaxy from the early universe that appears to have almost no rotation, a finding that is challenging current ideas about how galaxies form and evolve.
The galaxy, known as XMM-VID1-2075, formed when the universe was less than 2 billion years old. Despite its enormous size and mature structure, researchers found no evidence that it spins like most galaxies are expected to, according to the published study.
Scientists generally believe galaxies begin rotating naturally as gas collapses inward under gravity during formation. This creates angular momentum, causing galaxies to spin over time. Large galaxies with little rotation, known as “slow rotators,” are usually observed much later in cosmic history after billions of years of collisions and mergers disrupt their motion.
That is why XMM-VID1-2075 surprised astronomers. According to current theories, a galaxy this young should still retain strong rotational movement rather than displaying mostly random stellar motion.
The discovery was made by researchers involved in the MAGAZ3NE survey, which focuses on massive ancient galaxies in the distant universe. Earlier observations from the W. M. Keck Observatory had already confirmed that the galaxy was unusually massive for its age and had largely stopped forming new stars.
Using Webb’s infrared instruments, scientists were able to study the internal movement of material inside the galaxy in much greater detail than previously possible for such distant objects.
The research team examined three early galaxies from the same era. One showed clear rotation, another appeared highly irregular, and XMM-VID1-2075 stood out because its stars moved in random directions rather than orbiting around a central rotational axis.
Researchers are now trying to determine what could have disrupted the galaxy’s spin so early in cosmic history. One leading possibility is that the galaxy experienced a major collision with another large galaxy rotating in the opposite direction. Such an event could theoretically cancel out much of the overall rotation.
Astronomers also observed an unusual excess of light near the galaxy, which may indicate the remains of another object interacting with it during the past.
The findings could help scientists test and refine computer simulations of galaxy evolution. Some existing models predicted that a small number of non-rotating galaxies might appear early in the universe, but researchers expected them to be extremely rare.
The discovery also highlights the growing role of the James Webb Space Telescope in studying the distant universe. Because ancient galaxies appear extremely small and faint from Earth, observing their internal motion was previously difficult even with the largest ground-based observatories.
Now, Webb is allowing astronomers to examine how galaxies behaved during the universe’s earliest periods with a level of detail that was previously impossible.
For scientists studying galaxy formation, the discovery raises an uncomfortable but exciting possibility: some galaxies may have evolved much faster, and much differently, than existing theories predicted.
