Tiny glowing objects discovered at the dawn of the universe baffle scientists

A recent discovery by NASA’s James Webb Space Telescope (JWST) has confirmed that bright, very red objects previously detected in the early universe are upending conventional wisdom about the origins and evolution of galaxies and their supermassive black holes.

An international team, led by Penn State researchers, using the NIRSpec instrument aboard JWST as part of the RUBIES survey has identified three mysterious objects in the early universe, about 600 to 800 million years after the Big Bang, when the universe was only 5 percent of its current age. They announced the discovery today, June 27, at Letters from the Astrophysical Journal.

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

The researchers also said they were surprised to discover signatures of huge supermassive black holes in the same objects, estimating that they are 100 to 1,000 times more massive than the supermassive black hole in our own Milky Way. Neither phenomenon is expected in current models of galaxy growth and supermassive black hole formation, which predict that galaxies and their black holes grow together over billions of years of cosmic history.

“We confirmed that they appear to be filled with ancient stars — hundreds of millions of years old — in a universe that is only 600 to 800 million years old. Remarkably, these objects hold the record for the earliest signatures of ancient starlight,” said Bingjie Wang, a postdoctoral researcher at Penn State and lead author of the paper.

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

Researchers first spotted the massive objects in July 2022, when the initial dataset was released by JWST. The team published an article in Nature several months later, announcing the objects’ existence.

At the time, researchers suspected these objects were galaxies, but continued their analysis by taking spectra to better understand the objects’ true distances, as well as the sources powering their immense light.

The researchers then used the new data to build a clearer picture of what the galaxies looked like and what they contained. Not only did the team confirm that the objects were indeed galaxies near the beginning of time, but they also found evidence of surprisingly large supermassive black holes and a surprisingly ancient population of stars.

“It’s very puzzling,” said Joel Leja, assistant professor of astronomy and astrophysics at Penn State and co-author of both papers. “You could make it fit poorly into our current model of the universe, but only if we’re talking about an exotic, incredibly rapid formation at the beginning of time. It’s, without a doubt, the most peculiar and interesting set of objects I’ve seen in my career.”

JWST is equipped with infrared detection instruments that can detect light emitted by the oldest stars and galaxies. In essence, the telescope allows scientists to peer back in time to about 13.5 billion years ago, near the beginning of the universe as we know it, Leja said.

One of the challenges of analyzing ancient light is that it can be difficult to differentiate between the types of objects that could have emitted that light. In the case of these primitive objects, they clearly exhibit the characteristics of supermassive black holes and old stars.

However, Wang explained, it is not yet clear how much observed light comes from each of them, meaning they could be early galaxies that are surprisingly old and more massive than our own Milky Way, forming much earlier than models predict, or that they could be more normal-mass galaxies with “supermassive” black holes, about 100 to 1,000 times more massive than such a galaxy would have today ‘today.

“It’s difficult to distinguish between light from matter falling into a black hole and light emitted by stars in these tiny, distant objects,” Wang said. “The inability to differentiate in current data leaves much room for interpretation of these intriguing objects. Honestly, it’s exciting to still have so much to unravel in this mystery. »

Their inexplicable mass and age aside, if some of the light does indeed come from supermassive black holes, then they aren’t normal supermassive black holes either. They produce many more ultraviolet photons than expected, and similar objects studied with other instruments lack the characteristic signatures of supermassive black holes, such as hot dust and bright X-ray emission. But perhaps the most surprising thing, researchers say, is their scale.

“Normally, supermassive black holes are associated with galaxies,” explains Leja. “They grow up together and experience all the great experiences of their lives together. But here we have a fully formed adult black hole living inside what should be a small galaxy. This doesn’t really make sense, because these things should grow together, or at least that’s what we thought. »

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

Leja explained that if you took the Milky Way and compressed it to the size of the galaxies found, the nearest star would be almost within 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 be so dense with stars, stars that must have formed in ways we’ve never seen, in conditions we would never expect during a time when we would never expect to see them,” Leja said. “And for whatever reason, the universe stopped making objects like these after just a few billion years. They’re unique to the early universe.”

Researchers hope to continue their observations, which could help solve some of the mysteries of these objects. They plan to obtain deeper spectra by pointing the telescope at the objects for extended periods, which will help disentangle emissions from stars and the potential supermassive black hole by identifying the specific absorption signatures that would be present in each.

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