NASA’s James Webb Space Telescope (JWST) recently revealed that brilliant, extremely red objects discovered in the early universe challenge traditional wisdom regarding the formation and evolution of galaxies and their supermassive black holes.
An multinational team lead by Penn State researchers used the NIRSpec instrument aboard JWST as part of the RUBIES survey to discover three mystery objects in the early cosmos, 600-800 million years after the Big Bang, when the universe was only 5% the age it is today. They published the discovery today (June 27) in Astrophysical Journal Letters.
The researchers investigated spectral measurements, or the intensity of various wavelengths of light emitted by the objects. Their investigation revealed the signs of “old” stars that are hundreds of millions of years old, much older than predicted in a young universe.
The researchers were also startled to find indications of large supermassive black holes in the same objects, which are estimated to be 100 to 1,000 times more massive than the supermassive black hole in our own Milky Way. Neither of these are predicted by current models of galaxy expansion and supermassive black hole formation, which assume that galaxies and black holes will grow together over billions of years of cosmic history.
“We have confirmed that these appear to be packed with ancient stars, hundreds of millions of years old, in a universe that is only 600-800 million years old.” Remarkably, these objects have the earliest signs of old starlight,” said Bingjie Wang, a Penn State postdoctoral scientist and the paper’s primary author. “It was completely unexpected to discover old stars in a relatively young universe. The traditional models of cosmology and galaxy formation have been extremely effective, but these brilliant objects do not fit neatly into those theories.”
The scientists discovered the enormous objects in July 2022, when the inaugural JWST dataset was released. The researchers released a report in Nature several months later, announcing the objects’ existence.
At the time, the astronomers assumed the objects were galaxies, but they continued their investigation by collecting spectra to better grasp the real distances of the objects and the sources of their immense luminosity.
The researchers then used the new data to gain a better understanding of what the galaxies looked like and what was inside them. The researchers not only confirmed that the objects were galaxies near the beginning of time, but they also discovered evidence of very huge supermassive black holes and an unusually old population of stars.
“It’s very confusing,” said Joel Leja, an assistant professor of astronomy and astrophysics at Penn State who co-authored both publications. “You can fit this uncomfortably into our existing model of the universe, but only if we imagine some unusual, extremely quick formation at the beginning of time. This is without a doubt the most unusual and intriguing collection of artifacts I’ve seen in my career.”
The JWST is outfitted with infrared sensors capable of detecting light generated by the most ancient stars and galaxies. Essentially, the telescope allows scientists to see back in time around 13.5 billion years, close to the beginning of the universe as we know it, according to Leja.
One issue in evaluating ancient light is distinguishing between the several types of things that could have emitted the light. These early objects have properties similar to both supermassive black holes and ancient stars. However, Wang explained that it is unclear how much of the observed light comes from each, implying that these could be early galaxies that are unexpectedly old and more massive than our own Milky Way, forming far earlier than models predict, or they could be more normal-mass galaxies with “overmassive” black holes, which are roughly 100 to 1,000 times more massive than such a galaxy would have today.
Researchers have discovered that supermassive black holes, which are characterized by their unexplainable mass and age, produce more ultraviolet photons than expected and lack the characteristic signatures of supermassive black holes. The discovery also suggests that these objects are not paired with galaxies, as they appear to be living inside a baby galaxy, which is unusual, as these objects typically grow together.
Reference : https://www.sciencedaily.com/releases/2024/06/240628125241.htm
