An international team of 48 astronomers led by the University of Massachusetts Amherst has identified galaxies formed just one billion years after the Big Bang, potentially rewriting our understanding of cosmic history. The research, published in The Astrophysical Journal Letters on February 17, 2026, reveals a population of previously unknown, dusty star-forming galaxies dating back almost 13 billion years. These galaxies appear to bridge the gap between the earliest bright galaxies and older, “quiescent” galaxies, offering a crucial “snapshot” in galactic evolution. “It’s as if we now have snapshots of the lifecycle of these rare galaxies,” says Jorge Zavala, assistant professor of astronomy at UMass Amherst and the paper’s lead author, suggesting star formation occurred earlier in the universe than current models predict.
\nALMA and JWST Identify 13-Billion-Year-Old Dusty Galaxies
\nSubsequent near-infrared observations from NASA’s James Webb Space Telescope then allowed them to pinpoint approximately 70 faint candidates at the universe’s edge, many unseen until now. By revisiting the ALMA data and “stacking” observations, the team definitively confirmed these galaxies formed almost 13 billion years ago. These discoveries are challenging existing cosmological models, suggesting star formation began earlier in the universe than previously understood. The dust itself, which absorbs ultraviolet and visible light, previously obscured these galaxies from traditional telescopes, but submillimeter telescopes reveal the infrared energy emitted as the dust heats up.
\nDust Obscuration Resolved with Submillimeter Telescopes
\nThe ability to observe the universe’s earliest galaxies has undergone a revolution, thanks to advancements in submillimeter telescope technology. For decades, understanding galaxy formation in the immediate aftermath of the Big Bang—which occurred 13.7 billion years ago—was hampered by pervasive cosmic dust. This dust absorbs ultraviolet and visible light, rendering many galaxies invisible to traditional telescopes. However, the development of instruments capable of detecting longer wavelengths has pierced this veil, revealing previously hidden populations of galaxies.
\nGalaxies Link Ultrabright Sources to Early “Quiescent” Systems
\n“My research involves trying to identify and understand a population of rare, dusty star-forming galaxies that were only discovered at the end of the 1990s,” Zavala explains. The team initially identified approximately 400 bright, dusty galaxies using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, then pinpointed around 70 faint candidates with NASA’s James Webb Space Telescope. These galaxies appear to connect the recently discovered ultrabright galaxies, formed 13.3 billion years ago, with the early “quiescent” galaxies that ceased star formation roughly 2 billion years after the Big Bang.
\n\n\n \n\nThe detection of these early, dusty systems relies heavily on measuring the redshift of their emitted radiation. Redshift is the fractional change in the observed wavelength of light from distant sources, caused by the expansion of the universe. By analyzing how much visible light has been stretched into the infrared band, astronomers can calculate the precise distance and lookback time, placing these galaxies accurately within the cosmic timeline and confirming their early formation epoch.
\nThe presence of abundant metals, derived from stellar evolution and galactic enrichment, is particularly significant. These metals are necessary building blocks for the complex stellar populations observed in mature galaxies. Understanding the rate at which these metals accumulate in the early universe provides crucial constraints on the efficiency of the first generation of massive stars, known as Population III stars, which fundamentally seeded the cosmos with heavy elements.
\nFurthermore, the observed characteristics suggest that early galaxy growth may have been dominated by mergers of smaller, proto-galactic fragments. These accretion events provide the raw material and gravitational impetus for intense starbursts, leading to the massive dust clouds necessary for the subsequent deep infrared detections. Modeling these early merger dynamics is key to developing next-generation cosmological simulations.
\nThe technical challenge of disentangling background sources and foreground contamination remains a critical frontier. High-resolution spectroscopic data is required to differentiate the redshifted emissions from distant target galaxies versus foreground galactic material, demanding extremely precise data processing and advanced machine learning algorithms applied to the massive data streams provided by telescopes like ALMA and JWST.
\nDusty galaxies are massive galaxies with large amounts of metals and cosmic dust.
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