Webb discovers ancient galaxies that defy explanation

Three mysterious objects of the early universe

Researchers examined three mysterious objects in the early universe. Shown here are color images of them, combined with three NIRCam filter bands on the James Webb Space Telescope. They are remarkably dense at red wavelengths (leading to them being called “little red dots”), with some evidence of spatial structure at blue wavelengths. Credit: Bingjie Wang/Penn State

NASA'S James Webb Space Telescope Mysterious objects have been discovered in the early universe that challenge current theories of galaxies and supermassive objects Black holes Development.

These objects contain old stars and supermassive black holes that are much more massive than expected, suggesting a rapid and unconventional form of early galaxy formation. The findings highlight important discrepancies with existing models, and the objects' unique properties indicate a complex early cosmic history.

Important discoveries in the early universe

A recent discovery by NASA's James Webb Space Telescope (JWST) confirms previously discovered bright, very red objects in the early universe and upends established ideas about the origin and evolution of galaxies and their supermassive black holes.

Led by Penn State researchers and using the NIRSpec instrument on JWST as part of the RUBIES survey, the international team identified three mysterious objects that date back 600-800 million years to Earth. big BangA time when the universe was just 5% of its current age. They announced the discovery on June 27 in the journal Astrophysical Journal Letters,

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

Artist's depiction of the James Webb Space Telescope

The James Webb Space Telescope (JWST) offers a glimpse into the universe's distant past, capturing images of the universe's first galaxies and stars that formed 13.5 billion years ago. Credit: NASA-GSFC, Adriana M. Gutierrez (CI Lab)

Unexpected discoveries in galaxy evolution

The researchers said they were also surprised to find signs of supermassive black holes in the same objects, estimating them to be 100 to 1,000 times more massive than our own supermassive black hole. GalaxyNeither of these is expected in current models of galaxy evolution and supermassive black hole formation, which expect galaxies and their black holes to evolve together over billions of years of cosmic history.

“We confirmed that these appear to be full of ancient stars — hundreds of millions of years old — in a universe that is only 600-800 million years old. Remarkably, these objects record the earliest signs of light from old stars,” said Bingjie Wang, a postdoctoral scholar at Penn State and lead author of the paper. “Finding old stars in a very young universe was completely unexpected. Standard models of cosmology and galaxy formation have been incredibly successful, yet, these luminous objects do not fit perfectly into those theories.”

Researchers first observed these giant objects in July 2022, when the initial dataset from JWST was released. The team published a paper in 2022. Nature The existence of these objects was announced several months later.

Challenges in cosmic observation

At the time, researchers suspected these objects were galaxies, but they continued their analysis by taking spectra to better understand the objects' true distances, as well as the sources driving the objects' enormous luminosities.

The researchers 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 these objects were indeed galaxies from near the beginning of time, but they also found evidence for 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 a co-author of both papers. “You can fit this uncomfortably into our current universe model, but only if we postulate some bizarre, insanely fast structure at the beginning of time. This is, without a doubt, the strangest and most interesting set of objects I've seen in my career.”

james webb space telescope cold side

The JWST is designed to observe events that occurred shortly after the Big Bang, using its advanced infrared capabilities to see through cosmic dust and uncover hidden structures in space. Credit: Northrop Grumman

Mysteries of ancient galaxy structures

The JWST carries infrared-sensing instruments capable of detecting light emitted by the most ancient stars and galaxies. Basically, the telescope allows scientists to look back in time about 13.5 billion years, which is close to the beginning of the universe, Leja said.

One challenge in analyzing ancient light is that it can be hard to distinguish between 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's not yet clear how much light comes from each — meaning these could be early galaxies that are unexpectedly older and even more massive than our own galaxy, formed much earlier than models predict, or they could be more normal-mass galaxies with “supermassive” black holes, about 100 to 1,000 times more massive than such galaxies today.

“It's challenging to distinguish between the light emitted by matter falling into the black hole and the light emitted by stars in these small, distant objects,” Wang said. “The inability to tell the difference in the current dataset leaves a lot of room for interpretation of these interesting objects. Honestly, it's thrilling to have so much of this mystery unraveled.”

Besides their unexplained mass and age, if some of the light does indeed come from supermassive black holes, they are also not typical supermassive black holes. 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, researchers said, is just how huge they appear to be.

“Usually supermassive black holes are associated with galaxies,” Leja said. “They grow up together and go through all the big experiences of their lives together. But here, we have a fully grown adult black hole living inside a baby galaxy. It doesn't really make sense, because these things are supposed to grow together, or at least that's what we thought.”

The researchers were also surprised by the incredibly small size of these systems, which were only a few hundred light-years in diameter, about 1,000 times smaller than our own galaxy. These stars are roughly equal in number to our own galaxy, the Milky Way – which has about 10 billion to 1 trillion stars – but their volume is 1,000 times smaller than the Milky Way.

Leja explained that if you take the Milky Way and compress it to the size of the galaxies they discovered, the nearest star would be roughly the size of our solar system. The supermassive black hole at the center of the Milky Way, which is about 26,000 light-years away, would be only 26 light-years from Earth and would appear as a giant pillar of light in the sky.

“These early galaxies would have been so dense with stars — stars that formed in ways we've never seen, under conditions we'd never expect, and at a time period when we wouldn't expect to see them,” Leja said. “And for whatever reason, the universe stopped forming such objects after only a few billion years. They're unique to the early universe.”

The researchers hope to make more observations that may help them understand the mysteries of these objects. They plan to take more in-depth spectra by focusing the telescope on these objects for longer periods of time, which will help separate the emissions from stars and potential supermassive black holes, as this will identify the specific absorption signatures present in each.

“There is another way we can achieve success, and it is absolutely the right idea,” Leza said. “We have all the pieces of the puzzle and they fit together only if we ignore the fact that some of them are breaking. This problem can be solved with the help of a genius who has so far eluded us, all our colleagues and the entire scientific community.”

Reference: “Rubies: Evolved stellar populations with extended formation histories at z ∼ 7–8 in candidate massive galaxies detected with JWST/NIRSPEC” by Bingjie Wang, 冰洁王, Joel Leja, Anna de Graaff, Gabriel B. Brammer, Andrea Weibel, Peter van Dokkum, Josephine F.W. Bagen, Katherine A. Suess, Jenny E. Green, Rachel Bezanson, Nico J. Clary, Michaela Hirschmann, Ivo Labbe, Jorit Mathy, Ian McConnachie, Rohan P. Naidu, Erica Nelson, Pascal A. Oesch, David J. Seton and Christina C. Williams, 26 June 2024, Astrophysical Journal Letters,
DOI: 10.3847/2041-8213/ad55f7

Wang and Leja received funding from NASA's General Observer Program. The research was also supported by the International Space Science Institute in Bern. The work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The calculations for the research were performed on the Roar supercomputer at Penn State's Institute for Computational and Data Sciences.

Other co-authors of the paper are Anna de Graaff of the Max-Planck-Institut für Astronomie in Germany; Gabriele Brammer of the Cosmic Dawn Center and the Niels Bohr Institute; Andrea Weibel and Pascal Oesch of the University of Geneva; Nico Clary, Michaela Hirschmann, Peter van Dokkum and Rohan Naidu. Yale University; Ivo Labbe of Stanford University; Jorit Mathie and Jenny Green Princeton University; Ian McConnachie and Rachel Bezanson of the University of Pittsburgh; Josephine Bagnas of Texas A&M University; Catherine Suess of Observatoire de Sauvergy, Switzerland; David Setton of the Kavli Institute for Astrophysics and Space Research of the Massachusetts Institute of Technology; Erica Nelson of the University of Colorado; Christina Williams of the US National Science Foundation's National Optical-Infrared Astronomy Research Laboratory and the University of Arizona.

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