Today's discovery by NASA's James Webb Space Telescope (JWST) has revealed glowing, very red objects in the early universe that challenge conventional thinking about the formation and evolution of galaxies and their supermassive black holes.

An international team led by researchers from Penn State, using the NIRSpec instrument on JWST as part of the RUBIES study, identified three mysterious objects in the early universe, about 600-800 million years after the Big Bang, when the universe was only 5% of its current age. The discovery was published on June 27 in the journal Astrophysical Journal Letters.

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

Researchers were also surprised by the discovery of signatures of large 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 Milky Way. None of these findings were expected according to 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 these objects are filled with ancient stars - hundreds of millions of years old - in a universe only 600-800 million years old. Incredibly, these objects hold the record for the earliest signatures of old stellar light," said Bingjie Wang, a postdoctoral researcher at Penn State and the lead author of the paper. “It was completely unexpected to find old stars in a very young universe. Standard models of cosmology and galaxy formation have been incredibly successful, but these bright objects do not fit into those theories.”

Researchers first spotted the massive objects in July 2022, when JWST released its initial data set. The team published a paper in the journal Nature a few months later, announcing the existence of the objects.

At the time, researchers suspected the objects were galaxies but continued with spectral analysis to better understand the true distances of the objects as well as the sources of their immense light.

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

“It is very confusing,” said Joel Leja, assistant professor of astronomy and astrophysics at Penn State and co-author of both papers. “You can uncomfortably fit them into our current model of the universe, but only if you invoke some exotic, incredibly fast formation at the beginning of time. This is, without a doubt, the most peculiar and interesting set of objects I have seen in my career.”

JWST is equipped with instruments for detecting infrared light that can reveal the light emitted by the oldest stars and galaxies. Essentially, the telescope allows scientists to look back about 13.5 billion years, near the beginning of the universe as we know it, Leja said.

One of the challenges in analyzing ancient light is that it can be difficult to distinguish the types of objects that could have emitted the light. In the case of these early objects, they have clear characteristics of both supermassive black holes and old stars. However, Wang explained, it is still unclear how much light comes from each source - meaning these could be early galaxies that are unexpectedly old and more massive even than our Milky Way, forming much earlier than models predict, or they could be normal galaxies with "too massive" black holes, about 100 to 1,000 times more massive than such a galaxy would have today.

“Differentiating the light coming from material falling into a black hole and the light emitted by stars in these small, distant objects is challenging,” Wang said. “That inability to distinguish in current data leaves much room for interpretation of these intriguing objects. Honestly, it is exciting to have so much to solve.”

Besides their unexplained mass and age, if part of the light indeed comes from supermassive black holes, then they are also not normal supermassive black holes. They produce much more ultraviolet photons than expected, and similar objects studied with other instruments do not have the characteristic signatures of supermassive black holes, such as hot dust and strong X-ray emissions. But perhaps most surprisingly, they are incredibly massive, researchers said.

“Normally, supermassive black holes are paired with galaxies,” Leja said. “They grow together and go through all their major life stages together. But here we have a fully formed adult black hole within what should be a baby galaxy. It does not make sense because these things should grow together, or at least so we thought.”

Researchers were also puzzled by the incredibly small sizes of these systems, only a few hundred light-years in diameter, roughly 1,000 times smaller than our Milky Way. The stars are about as numerous as in our Milky Way - with somewhere between 10 billion and 1 trillion stars - but contained within 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 they found, the nearest star would almost be 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 visible in the sky as a giant pillar of light.

“These early galaxies would be so dense with stars - stars that had to form in a way we have never seen, under conditions we would never expect during a period we would never expect to see them,” Leja said. “And for some reason, the universe stopped making such objects after only a few billion years. They are unique to the early universe.”

Researchers hope for further observations, which they say could help explain some of the mysteries of these objects. They plan to take deeper spectra by pointing the telescope at the objects for longer periods, which will help distinguish the emission from stars and potential supermassive black holes by identifying specific absorption signatures that would be present in each of them.

“There is another way we could make a breakthrough, and that is simply the right idea,” Leja said. “We have all these puzzle pieces, and they fit only if we ignore the fact that some of them are broken. This problem is ripe for a genius move that has so far eluded us, all our collaborators, and the entire scientific community.”

Wang and Leja received funding from NASA's General Observers program. The research is also supported by the International Space Science Institute in Bern. The work is partly based on observations made using the NASA/ESA/CSA James Webb Space Telescope. The calculations for the research were conducted on the Roar supercomputer of the Institute for Computational and Data Sciences at Penn State.

Other co-authors of the paper are Anna de Graaff from the Max Planck Institute for Astronomy in Germany; Gabriel Brammer from the Cosmic Dawn Center and the Niels Bohr Institute; Andrea Weibel and Pascal Oesch from the University of Geneva; Nikko Cleri, Michaela Hirschmann, Pieter van Dokkum, and Rohan Naidu from Yale University; Ivo Labbé from Stanford; Jorryt Matthee and Jenny Greene from Princeton; Ian McConachie and Rachel Bezanson from the University of Pittsburgh; Josephine Baggen from Texas A&M University; Katherine Suess from the Observatoire de Sauverny in Switzerland; David Setton from the Kavli Institute for Astrophysics and Space Research at MIT; Erica Nelson from the University of Colorado; Christina Williams from the National Optical-Infrared Astronomy Research Laboratory of the U.S. National Science Foundation and the University of Arizona.

Source: Pennsylvania State University