May 29, 2026 01:28 AM
https://www.eurekalert.org/news-releases/1130005
EXCERPTS: Astronomical observations show that the most massive galaxies in the early Universe formed approximately 3 to 4 billion years after the Big Bang and stopped producing stars very early in cosmic history, around 1 billion years after their formation. This strange behavior has puzzled experts in the field. For comparison, our galaxy, the Milky Way, is as old as the Universe itself and continues to produce stars, albeit at a low rate, even 13.5 billion years after its formation.
A study conducted at the Institute of Astronomy, Geophysics, and Atmospheric Sciences at the University of São Paulo (IAG-USP) in Brazil, in collaboration with international partners and published in the journal Astronomy & Astrophysics, proposes a consistent solution to this problem.
“We focused on two seemingly distinct populations: dusty star-forming galaxies [DSFGs] and massive quiescent galaxies [MQs],” says Laerte Sodré Júnior, a retired full professor, former director of IAG-USP, and doctoral advisor to the lead author of the study, Pablo Araya-Araya.
[...] The study proposes that each progenitor galaxy of an MQ underwent an early and violent merger with a galaxy of similar mass. This catastrophic event triggered two simultaneous processes: an extreme burst of star formation and rapid growth of a supermassive black hole in the central region. “The merger of the two galaxies concentrated large amounts of gas in the core, simultaneously triggering an extreme burst of star formation and intense feeding of the supermassive black hole,” Sodré summarizes.
“In that process, the cold gas is rapidly consumed while the energy released by the active nucleus heats the surrounding halo gas and prevents it from cooling and being reincorporated into the galaxy, blocking the supply of raw material for new stars and halting star formation in less than one billion years,” the scientist explains.
In contrast, most star- and dust-forming galaxies grow more gradually through long-term processes. Significant mergers only occur at later stages, resulting in slower gas consumption and eventual late extinction of star formation, which is observed at lower redshifts.
[...] Recent operations of the James Webb Space Telescope have helped map DSFGs. At the same time, they revealed a greater-than-expected number of massive, quiescent galaxies in the early Universe.
The proposed model has not yet fully resolved the problem, as there are still discrepancies between predictions and observations. “We’re observing far more galaxies with submillimeter emissions than we predicted,” Sodré admits.
Nevertheless, the study provides a coherent framework for explaining the evolution of DSFGs into MQs based on galaxy mergers, bursts of star formation, and the formation of supermassive black holes... (MORE - missing details, no ads)
EXCERPTS: Astronomical observations show that the most massive galaxies in the early Universe formed approximately 3 to 4 billion years after the Big Bang and stopped producing stars very early in cosmic history, around 1 billion years after their formation. This strange behavior has puzzled experts in the field. For comparison, our galaxy, the Milky Way, is as old as the Universe itself and continues to produce stars, albeit at a low rate, even 13.5 billion years after its formation.
A study conducted at the Institute of Astronomy, Geophysics, and Atmospheric Sciences at the University of São Paulo (IAG-USP) in Brazil, in collaboration with international partners and published in the journal Astronomy & Astrophysics, proposes a consistent solution to this problem.
“We focused on two seemingly distinct populations: dusty star-forming galaxies [DSFGs] and massive quiescent galaxies [MQs],” says Laerte Sodré Júnior, a retired full professor, former director of IAG-USP, and doctoral advisor to the lead author of the study, Pablo Araya-Araya.
[...] The study proposes that each progenitor galaxy of an MQ underwent an early and violent merger with a galaxy of similar mass. This catastrophic event triggered two simultaneous processes: an extreme burst of star formation and rapid growth of a supermassive black hole in the central region. “The merger of the two galaxies concentrated large amounts of gas in the core, simultaneously triggering an extreme burst of star formation and intense feeding of the supermassive black hole,” Sodré summarizes.
“In that process, the cold gas is rapidly consumed while the energy released by the active nucleus heats the surrounding halo gas and prevents it from cooling and being reincorporated into the galaxy, blocking the supply of raw material for new stars and halting star formation in less than one billion years,” the scientist explains.
In contrast, most star- and dust-forming galaxies grow more gradually through long-term processes. Significant mergers only occur at later stages, resulting in slower gas consumption and eventual late extinction of star formation, which is observed at lower redshifts.
[...] Recent operations of the James Webb Space Telescope have helped map DSFGs. At the same time, they revealed a greater-than-expected number of massive, quiescent galaxies in the early Universe.
The proposed model has not yet fully resolved the problem, as there are still discrepancies between predictions and observations. “We’re observing far more galaxies with submillimeter emissions than we predicted,” Sodré admits.
Nevertheless, the study provides a coherent framework for explaining the evolution of DSFGs into MQs based on galaxy mergers, bursts of star formation, and the formation of supermassive black holes... (MORE - missing details, no ads)