Tiny bright objects discovered at the dawn of space have baffled scientists

A recent discovery by NASA’s James Webb Space Telescope (JWST) confirmed that luminous, very red objects previously detected in the early universe overturn conventional thinking about the origin and evolution of galaxies and their supermassive black holes.

Using the NIRSpec instrument aboard JWST as part of the RUBIES survey, an international team led by Penn State researchers identified three mysterious objects in the early universe, about 600-800 million years after the Big Bang, when the universe was just 5% of its current age. They announced the discovery today, June 27 Astrophysical Journal Letters.

The team studied spectral measurements, or the intensity of different wavelengths of light emitted by objects. Their analysis found signatures of “old” stars, hundreds of millions of years old, much older than expected in the young universe.

The researchers said they were also surprised to find signs of giant supermassive black holes in the same objects, which they estimate are 100 to 1,000 times more massive than the supermassive black hole in our own Milky Way. Neither of these is expected in current models of galaxy growth and supermassive black hole formation, which expect galaxies and their black holes to grow together over billions of years of cosmic history.

“We have confirmed that they appear to be packed with ancient stars – hundreds of millions of years old – in a universe that is only 600-800 million years old. It is remarkable that these objects hold the record for the first signs of old starlight.” said Bingjie Wang, a postdoctoral fellow at Penn State and lead author of the paper.

“It was completely unexpected to find old stars in a very young universe. The standard models of cosmology and galaxy formation have been incredibly successful, but these luminous objects don’t fit very comfortably into those theories.”

Scientists first spotted the massive objects in July 2022, when the initial data set was released from JWST. The team published an article in Nature a few months later he announced the existence of the objects.

At the time, scientists assumed the objects were galaxies, but they followed up their analysis by taking spectra to better understand the objects’ true distances, as well as the sources powering their massive light.

The scientists then used the new data to paint a clearer picture of what the galaxies looked like and what was inside them. Not only did the team confirm that the objects were indeed galaxies at the beginning of time, they also found evidence of surprisingly large supermassive black holes and a surprisingly old population of stars.

“It’s very confusing,” said Joel Leja, assistant professor of astronomy and astrophysics at Penn State and co-author of both papers. “You can fit it uncomfortably into our current model of the universe, but only if we conjure up some exotic, insanely fast formation at the beginning of time. This is without a doubt the strangest and most interesting set of objects I’ve ever known.” see in my career.”

JWST is equipped with infrared sensors capable of detecting the light that was emitted by the oldest stars and galaxies. The telescope essentially allows scientists to see back in time roughly 13.5 billion years, near the beginning of the universe as we know it, Leja said.

One of the problems with analyzing ancient light is that it can be difficult to distinguish between the types of objects that may have emitted light. In the case of these early objects, they have clear characteristics of both supermassive black holes and old stars.

However, Wang explained that it’s not yet clear how much of the observed light comes from each — meaning they could be early galaxies that are unexpectedly old and more massive, even than our own Milky Way, forming much earlier than the models they predict, or there could be more normal-mass galaxies with “supermassive” black holes, roughly 100 to 1000 times more massive than such a galaxy would be today.

“Distinguishing between light from material falling into a black hole and light emitted from stars in these small, distant objects is challenging,” Wang said. “This inability to tell the difference in the current data set leaves wide room for interpretation of these interesting objects. Frankly, it’s exciting to have so much of this mystery to unravel.”

In addition to their inexplicable mass and age, if some of the light does indeed come from supermassive black holes, then they are not normal supermassive black holes either. They produce far more ultraviolet photons than expected, and similar objects studied with other instruments lack the hallmarks of supermassive black holes, such as hot dust and bright X-ray emission. But perhaps the most surprising thing, the researchers said, is how massive they appear to be.

“Normally, supermassive black holes are paired with galaxies,” Leja said. “They grow up together and go through all their major life experiences together. But here we have a fully formed adult black hole living inside what should be a baby galaxy. That doesn’t really make sense because these things are supposed to grow together.” or so we thought.”

Researchers have also been baffled by the incredibly small size of these systems, only a few hundred light-years across, roughly 1,000 times smaller than our own Milky Way. The stars are about as numerous as our own Milky Way galaxy—with somewhere between 10 billion and 1 trillion stars—but they are in a volume 1,000 times smaller than the Milky Way.

Leia explained that if you took the Milky Way and compressed it to the size of the galaxies they found, the nearest star would be almost in our solar system. The supermassive black hole at the center of the Milky Way, about 26,000 light-years away, would be only about 26 light-years from Earth and would be visible in the sky as a giant pillar of light.

“These early galaxies would have been so dense with stars — stars that must have formed in a way we’ve never seen, under conditions we’d never expect at a time when we’d never expect to see them,” Leja said. “And for whatever reason, the universe stopped producing objects like these after a few billion years. They’re unique to the early universe.”

Scientists hope to follow up with more observations, which they say could help explain some of the mysteries of the objects. They plan to take deeper spectra by pointing the telescope at the objects for longer periods of time, which will help separate emission from stars and potential supermassive black holes by identifying specific absorption signatures that would be present in each.

“There is another way we could achieve a breakthrough, and this is the right idea,” Leja said. “We have all these pieces of the puzzle, and they only fit if we ignore the fact that some of them break. This problem is open to a touch of genius that has so far eluded us, all our collaborators, and the entire scientific community.”