Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have identified a supernova explosion linked to gamma-ray burst event GRB 250314A at a redshift of 7.3, occurring when the universe was merely 730 million years old. The previous record-holder for supernovae was observed when the universe reached 1.8 billion years. This discovery is detailed in two papers published in the journal Astronomy and Astrophysics.
Webb identified the origin of the blinding flashes known as gamma-ray bursts. This particular gamma-ray burst exploded when the universe was merely 730 million years old. Image credit: NASA / ESA / CSA / STScI / A. Levan, IMAPP / A. Pagan, STScI.
“Only Mr. Webb has directly demonstrated that this light is from a collapsing massive star,” stated Dr. Andrew Levan, an astronomer at Radboud University and the University of Warwick, and lead author of one of the papers.
“This observation suggests that we can utilize Webb to detect individual stars from a time when the universe was just 5% of its current age.”
Whereas gamma-ray bursts typically last from seconds to minutes, supernovae rapidly brighten over several weeks before slowly dimming.
In contrast, the supernova linked to GRB 250314A took months to brighten.
Because this explosion occurred so early in the universe’s history, its light continued to evolve as the universe expanded over billions of years.
As the light stretches, the duration for events to unfold also lengthens.
Webb’s observations were intentionally made three and a half months after the closure of the GRB 250314A event, as it was expected that the supernova would be at its brightest at this time.
“Webb provided the rapid and sensitive follow-up we so desperately needed,” remarked Dr. Benjamin Schneider, an astronomer at the Marseille Institute of Astrophysics.
Gamma-ray bursts are exceedingly rare. Bursts lasting only a few seconds may originate from the collision of two neutron stars or a neutron star and a black hole.
Longer bursts, like this one, which lasted around 10 seconds, are often linked to the explosions of massive stars.
On March 14, 2025, the SVOM mission—a joint Franco-Chinese telescope launched in 2024 designed to spot fleeting events—will detect gamma-ray bursts from extremely distant sources.
Within an hour and a half, NASA’s Neil Gehrels Swift Observatory had pinpointed the X-ray source in the sky, facilitating follow-up observations to measure the distance of the web.
Eleven hours later, Nordic optical telescopes revealed the afterglow of the infrared gamma-ray burst, indicating that gamma rays may correspond to very distant objects.
Four hours later, ESO’s Very Large Telescope estimated that the object existed 730 million years after the Big Bang.
“Only a handful of gamma-ray bursts have been identified in the first billion years of the universe and merely a few in the last 50 years,” Levan noted.
“This remarkable event is exceedingly rare and thrilling.”
As this is the oldest and most distant supernova ever identified, researchers compared it to nearby modern supernovae, finding surprising similarities.
Why? Little is still understood about the early billion years of the universe.
Early stars likely lacked heavy elements, were massive, and had brief lifespans.
They also existed during the reionization era, when intergalactic gas was almost opaque to high-energy light.
“Dr. Webb has demonstrated that this supernova resembles modern supernovae very closely,” stated Professor Nial Tanvir from the University of Leicester.
“Webb’s findings indicate that this distant galaxy is akin to other galaxies of the same epoch,” commented Dr. Emeric Le Floch, an astronomer at CEA Paris-Saclay.
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AJ Levan et al. 2025. JWST reveals a supernova following a gamma-ray burst at z ≃ 7.3. A&A 704, L8; doi: 10.1051/0004-6361/202556581
B. Cordier et al. 2025. SVOM GRB 250314A at z ≃ 7.3: Exploding star in the reionization era. A&A 704, L7; doi: 10.1051/0004-6361/202556580
Source: www.sci.news
