Webb uncovers ancient galaxies that defy explanation

NASA‘with The James Webb Space Telescope revealed mysterious objects in the early universe that challenge current theories of galaxies and supermassives 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 findings highlight significant discrepancies with existing models, and the unique properties of the objects suggest a complex early cosmic history.

A breakthrough discovery in the early universe

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

An international team led by Penn State researchers and using the NIRSpec instrument on JWST as part of the RUBIES survey identified three mysterious objects dating from 600-800 million years after Big Bangat a time when the universe was only 5% of its current age. They announced the discovery in a newspaper on June 27 Astrophysical Journal Letters.

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

Unexpected findings in galactic evolution

The researchers said they were also surprised to find signs of huge supermassive black holes in the same objects, estimated to be 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 confirmed that they 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 earliest signatures of old starlight,” said Bingjie Wang, a postdoctoral fellow at Penn State and lead author of the paper. “It was totally 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 quite fit 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.

Challenges in space observation

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 most unique and interesting collection of objects I have seen in my career.”

Mysteries of ancient galactic structures

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. But Wang explained that it’s not yet clear how much of the observed light comes from each of them — meaning they could be early galaxies that are unexpectedly old and more massive, even than our own Milky Way, forming much earlier than models predict 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 ample room for interpretation of these interesting objects.” Honestly, it’s exciting to have so much of this mystery to solve.”

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 come 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 contained 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 during a period we’d never expect to see,” Leja said. “And for whatever reason, the universe stopped producing objects like these after only a few billion years. They are unique to the early universe.”

Scientists 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 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 you ignore the fact that some of them break. This problem is amenable to a touch of genius that has so far eluded us, all our collaborators, and the entire scientific community.”

Reference: “RUBIES: Evolved Stellar Populations with Extended Formation History at z ∼ 7–8 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 FW 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, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ad55f7

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

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