NEW YORK: The enigmatic glow of the early universe has puzzled scientists since the James Webb Space Telescope (Webb) started its operations last year. Recent discoveries challenged existing cosmological models, suggesting the existence of massive, mature galaxies during cosmic dawn. Researchers, however, have now uncovered the mystery without overturning established theories.
Using advanced computer simulations, scientists modeled the evolution of the earliest galaxies, revealing a unique pattern of star formation. Instead of a steady pace, star formation occurred in intermittent, intense bursts during the initial few hundred million years after the Big Bang. These bursts, leading to flashes of light, created the illusion of significant mass, even in relatively small galaxies.
“Astronomers can securely measure how bright those early galaxies are because photons (particles of light) are directly detectable and countable, whereas it is much more difficult to tell whether those galaxies are really big or massive. They appear to be big because they are observed to be bright,” explained Guochao Sun, a postdoctoral fellow in astronomy at Northwestern University.
Study on Bright Galaxies
Webb, operational since 2022, unexpectedly detected ten times more brilliantly glowing galaxies from cosmic dawn than theoretical models anticipated. These galaxies, previously perceived as anomalies, now fit into the existing cosmological framework.
“In our new paper, we show quantitatively using our simulations that the bursts of star formation produce flashes of light that can explain the very bright galaxies observed by Webb. And the reason this is so significant is that we explain these very bright galaxies without having to break the standard cosmological model,” stated Claude-André Faucher-Giguère, a senior author of the study and Northwestern University astrophysicist.
This groundbreaking research, conducted as part of the Feedback of Relativistic Environments (FIRE) project, focused on “bursty star formation.” Unlike large galaxies with stable star formation, smaller galaxies experienced cycles of intense starburst followed by supernova explosions, fueling subsequent bursts.
The findings shed light on the universe’s early stages, emphasizing the importance of Webb’s observations in challenging existing scientific understanding and propelling the field of astronomy forward.
