July 17, 2024

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Webb discovers ancient galaxies that defy explanation

Webb discovers ancient galaxies that defy explanation

Researchers have examined three mysterious objects in the early universe. Shown here are their color images, collected from three NIRCam filter bands on the James Webb Space Telescope. They are noticeably compressed at red wavelengths (earning them the term “little red dots”), with some evidence of spatial structure at blue wavelengths. Credit: Bingjie Wang/Penn State

NASA‘s James Webb Space Telescope Uncover mysterious objects in the early universe that challenge current theories of galaxies and massive planets. Black hole development.

These objects contain old stars and massive black holes, much larger than expected, suggesting a rapid and unconventional form of early galaxy formation. The results highlight significant discrepancies with current models, and the objects’ unique properties point to a complex early cosmic history.

Amazing discovery at the beginning of the universe

A recent discovery by NASA’s James Webb Space Telescope confirms that previously discovered extremely red luminous objects in the early universe challenge established ideas about the origins and evolution of galaxies and their supermassive black holes.

Led by researchers from Penn State and using the NIRSpec instrument on JWST as part of the RUBIES survey, the international team identified three mysterious objects dating back 600-800 million years after the great explosionat a time when the universe was only 5 percent 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 signatures of “old” stars, hundreds of millions of years old, much older than expected in the young universe.

Illustration of the James Webb Space Telescope by artist

The James Webb Space Telescope (JWST) offers a window into the distant past of the universe, capturing images of the first galaxies and stars in the universe, which formed more than 13.5 billion years ago. Image credit: NASA Goddard Space Center, Adriana M. Gutierrez (CI Lab)

Unexpected Discoveries in Galactic Evolution

The researchers said they were also surprised to find signs of 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 galaxy. milky wayNone of this is expected in current models of galaxy growth and supermassive black hole formation, which predict galaxies and their black holes growing together over billions of years of universe history.

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“We confirmed that these objects 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 hold the record for the oldest signatures of ancient starlight,” said Benjie Wang, a postdoctoral researcher at Penn State and lead author of the study. “It was completely unexpected to find such ancient stars in such a young universe. The standard models of cosmology and galaxy formation have been incredibly successful, yet these luminous objects do not fit comfortably into these theories.”

Researchers first discovered the massive objects in July 2022, when the initial dataset from JWST was released. The team published a research paper in nature After several months, the existence of these things was announced.

Challenges in cosmic observation

At the time, researchers suspected that these objects were galaxies, but they followed up their analysis by taking spectra to better understand the objects’ true distances, as well as the sources that fuel their enormous light.

The researchers 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 these galaxies were indeed galaxies close to the beginning of time, they also found evidence of surprisingly massive black holes and a surprisingly ancient population of stars.

“It’s very puzzling,” said Joel Lega, an assistant professor of astronomy and astrophysics at Penn State and a co-author of both papers. “You can make this fit uncomfortably with our current model of the universe, but only if you conjure up some crazy, crazy-fast configuration at the beginning of time. This is, without a doubt, the most bizarre and interesting collection of objects I’ve seen in my career.”

The cold side of the James Webb Space Telescope

The James Webb Space Telescope is designed to observe phenomena that occurred immediately after the Big Bang, using its advanced infrared capabilities to peer through cosmic dust and discover hidden structures in space. Copyright: Northrop Grumman

Secrets of ancient galactic structures

The James Webb Telescope is equipped with infrared sensors that can detect light emitted by the oldest stars and galaxies. This allows scientists to see back to about 13.5 billion years ago, near the beginning of the universe as we know it, Lega said.

One challenge with analyzing ancient light is that it can be difficult to distinguish between the types of objects that might have produced the light. In the case of these early objects, they have clear characteristics of both supermassive black holes and ancient stars. However, Wang explained, it is not yet clear how much of the observed light comes from each — meaning these could be unexpectedly old early galaxies that are even more massive than the Milky Way, and 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 a galaxy today.

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“Distinguishing the light from material falling into a black hole from the light from stars in these small, distant objects is extremely difficult,” Wang said. “The inability to tell the difference in the current dataset leaves a lot of room for interpretation of these interesting objects. Frankly, it’s exciting that so much of this mystery remains unsolved.”

Beyond their inexplicable mass and age, if some of the light is indeed coming from supermassive black holes, they are not ordinary 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 most surprising, the researchers said, is how massive they are.

“Usually supermassive black holes are associated with galaxies,” Leja said. “They grow together and go through all their major life experiences together. But here, we have a fully grown adult black hole living inside what should be a baby galaxy. That doesn’t really make sense, because these things should grow together, or at least that’s what we thought.”

The researchers are also puzzled by the extremely small size of these systems, which are only a few hundred light-years across, roughly a thousand times smaller than our own Milky Way galaxy. The number of stars in these systems is roughly the same as the number of stars in our own Milky Way galaxy—between ten billion and a trillion stars—but they are confined to a volume about a thousand times smaller than the Milky Way.

“If we took the Milky Way and squeezed it down to the size of the galaxies we’ve found, the nearest star would be almost exactly in our solar system,” Lega explained. The supermassive black hole at the center of the Milky Way, which is about 26,000 light-years away, would be only about 26 light-years away from Earth, and would be visible in the sky as a giant pillar of light.

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“These early galaxies were full of stars — stars that must have formed in a way we’ve never seen before, under conditions we never expected during a period when we never expected to see them,” Leja said. “For some reason, the universe stopped making things like this after only a few billion years. They’re unique in the early universe.”

The researchers hope to follow up with more observations, which they say could help explain some of the objects’ mysteries. They plan to take deeper spectra by pointing the telescope at the objects for long periods of time, which will help untangle the emissions from the stars and the possible supermassive black hole by identifying the specific absorption signatures that may be present in each.

“There is another way we can make a breakthrough, and that is the right idea,” said Lega. “We have all these pieces of the puzzle and we can only solve them if we ignore the fact that some of them might break. This problem is solvable with a stroke of genius that has so far eluded us, all of our colleagues and the entire scientific community.”

Reference: “RUBIES: Star clusters with extended formation histories at z ∼ 7–8 have evolved in candidate massive galaxies identified with JWST/NIRSpec” by Bingjie Wang, 冰洁王, Joel Leja, Anna de Graaff, Gabriel B. Brammer, Andrea Weibel, Pieter van Dokkum, Josephine F. W. Baggen, Katherine A. Suess, Jenny E. Greene, Rachel Bezanson, Nikko J. Cleri, Michaela Hirschmann, Ivo Labbé, Jorryt Matthee, Ian McConachie, Rohan P. Naidu, Erica Nelson, Pascal A. Oesch, David J. Setton and Christina C. Williams, 26 June 2024, Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ad55f7

Wang and Lega 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 James Webb Space Telescope, a collaboration of NASA, the European Space Agency, and the Canadian Space Agency. The calculations for the research were performed on the Rohr supercomputer at the Institute for Computational and Data Sciences at Pennsylvania State University.

Co-authors of the study include Anna de Graaf of the Max Planck Institute for Astronomy in Germany; Gabriele Brammer of the Cosmic Dawn Center and the Niels Bohr Institute; Andrea Weibel and Pascal Oesch of the University of Geneva; and Nico Cleary, Michaela Hirschmann, Peter van Dokkum and Rohan Naidoo of the University of Geneva. Yale University; Ivo Lappi of Stanford University; Jorit Mathy and Jenny Green of Princeton UniversityIan McConachie and Rachel Bezanson of the University of Pittsburgh; Josephine Pagen of Texas A&M University; Catherine Suss of the Souverny Observatory in Switzerland; David Seaton of the MIT Kavli Institute for Astrophysics and Space Research; Erica Nelson of the University of Colorado; and Christina Williams of the National Science Foundation’s National Optical and Infrared Astronomy Research Laboratory and the University of Arizona.