Researchers have discovered three ultra-massive galaxies from the universe’s first billion years, challenging existing models of star formation.
These galaxies, identified with the James Webb Space Telescope, exhibit unusually high star formation rates, suggesting more efficient early galaxy formation than previously thought.
Groundbreaking Galaxy Findings
An international team led by the University of Geneva (UNIGE), including Professor Stijn Wuyts from the University of Bath, has discovered three ultra-massive galaxies—each almost as massive as the Milky Way—that had already formed within the first billion years after the Big Bang.
Their findings suggest that star formation in the early Universe was far more efficient than previously believed, challenging existing models of galaxy formation.
This unexpected discovery, published on November 13 in the journal Nature, was made using data from the James Webb Space Telescope (JWST) as part of the JWST FRESCO program.
Advanced Techniques in Galaxy Research
The FRESCO program aimed to systematically analyze a complete sample of emission-line galaxies (ELGs) from the Universe’s first billion years. ELGs, which display prominent emission lines in their spectra (the range of light wavelengths they emit), show bright lines at specific wavelengths that stand out against a darker spectrum background.
The presence of emission lines enabled the team to accurately pin down the distances to the galaxies in the sample. In turn, precise knowledge of the distances and emission line strengths allowed the researchers to reliably measure the amount of stars contained within the galaxies. Three stood out by their large stellar content.
“Finding three such massive beasts among the sample poses a tantalizing puzzle,” said Professor Wuyts, co-author of the Nature study and Hiroko Sherwin Chair in Extragalactic Astronomy at Bath’s Department of Physics.
“Many processes in galaxy evolution have a tendency to introduce a rate-limiting step in how efficiently gas can convert into stars, yet somehow these Red Monsters appear to have swiftly evaded most of these hurdles.”
Implications for Galaxy Formation Models
Until now, it was believed that all galaxies formed gradually within large halos of dark matter. Dark matter halos capture gas (atoms and molecules) into gravitationally bound structures. Typically, 20% of this gas, at most, is converted into stars in galaxies. However, the new findings challenge this view, revealing that massive galaxies in the early Universe may have grown far more rapidly and efficiently than previously thought.
Detail in the FRESCO study was captured through ‘slitless spectroscopy’ with JWST’s Near Infrared Camera, a surveying method that allows light to be captured and unraveled into its constituent wavelengths for all objects in a field of view. This makes it an excellent method for measuring accurate distances and physical characteristics of galaxies.
Unveiling the “Red Monsters”
JWST’s unparalleled capabilities have allowed astronomers to systematically study galaxies in the very distant and early Universe, providing insights into massive and dust-obscured galaxies. By analyzing galaxies included in the FRESCO survey, scientists found that most galaxies fit existing models. However, they also found three surprisingly massive galaxies, with stellar masses comparable to today’s Milky Way.
These are forming stars nearly twice as efficiently as lower-mass galaxies from the same epoch or ordinary galaxies at later times in cosmic history. Due to their high dust content, which gives these three massive galaxies a distinct red appearance in JWST images, they have been named the three Red Monsters.
Dr. Mengyuan Xiao, lead author of the new study and postdoctoral researcher at UNIGE, said: “Our findings are reshaping our understanding of galaxy formation in the early Universe.”
Dr. David Elbaz, director of research at CEA Paris-Saclay and collaborator on this project, said: “The massive properties of these Red Monsters were hardly determined before JWST, as they are optically invisible due to dust attenuation.”
A Milestone in Galaxy Observations
Pascal Oesch, associate professor in the Department of Astronomy at the UNIGE, and principal investigator of the observation program, said: “Our findings highlight the remarkable power of NIRCam/grism spectroscopy. The instrument on board the space telescope allows us to identify and study the growth of galaxies over time, and to obtain a clearer picture of how stellar mass accumulates over the course of cosmic history.”
While these findings do not conflict with the standard cosmological model, they raise questions for galaxy formation theories, specifically the issue of ‘too many, too massive’ galaxies in the early Universe.
Current models may need to consider unique processes that allowed certain early massive galaxies to achieve such efficient star formation and thus form very rapidly, very early in the Universe. Future observations with JWST and the Atacama Large Millimeter Array (ALMA) telescope will provide further insights into these ultra-massive Red Monsters and reveal larger samples of such sources.
Dr. Xiao said: “These results indicate that galaxies in the early Universe could form stars with unexpected efficiency. As we study these galaxies in more depth, they will offer new insights into the conditions that shaped the Universe’s earliest epochs. The Red Monsters are just the beginning of a new era in our exploration of the early Universe.”
Professor Wuyts added: “That is what is so great about astronomy, we’re constantly being surprised by new discoveries. Already in its first few years of operation, JWST has thrown us a couple of curveballs. In more ways than one, it has shown us that some galaxies mature rapidly during the first chapters of cosmic history.”
For more on this discovery, see Mystery of the “Red Monsters”: Massive Early Galaxies That Shouldn’t Exist.
Reference: “Accelerated formation of ultra-massive galaxies in the first billion years” by Mengyuan Xiao, Pascal A. Oesch, David Elbaz, Longji Bing, Erica J. Nelson, Andrea Weibel, Garth D. Illingworth, Pieter van Dokkum, Rohan P. Naidu, Emanuele Daddi, Rychard J. Bouwens, Jorryt Matthee, Stijn Wuyts, John Chisholm, Gabriel Brammer, Mark Dickinson, Benjamin Magnelli, Lucas Leroy, Daniel Schaerer, Thomas Herard-Demanche, Seunghwan Lim, Laia Barrufet, Ryan Endsley, Yoshinobu Fudamoto, Carlos Gómez-Guijarro, Rashmi Gottumukkala, Ivo Labbé, Dan Magee, Danilo Marchesini, Michael Maseda, Yuxiang Qin, Naveen A. Reddy, Alice Shapley, Irene Shivaei, Marko Shuntov, Mauro Stefanon, Katherine E. Whitaker and J. Stuart B. Wyithe, 13 November 2024, Nature.
DOI: 10.1038/s41586-024-08094-5
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2 Comments
I read on a NASA site that the colours in images presented from the JWST infra red camera are false colours. Rather than showing black and white the images are coloured to suit the nearest visible colour, The red colour is nothing to do with dust clouds, the red shift at those distances is so large that the galaxies show only in infrared. Correct me if I am wrong. A bit of reading about the JWST should clarify the situation. I wont spoil the experience by explaining the details.
The false colours represent certain elements that are present.