A shockwave erupts from the star's surface, and for a brief moment, a blinding flash of ultraviolet and X-rays is born. This very event, named EP260321a, was spotted by the Einstein space telescope in March 2026. The light took about 450 million years to reach Earth.
Following the flash, astronomers saw supernova SN 2026gzf — the explosion of a massive star that had shed its outer layers. Its spectrum, brightness, and ejecta velocities matched exactly those of supernovae that typically accompany gamma-ray bursts — the most powerful explosions in the universe. Yet the Chandra X-ray telescope detected no afterglow: the narrow beam of energy that should have pierced space simply never appeared.
The authors propose a bridge scenario. Inside the star, a weak outflow likely formed — not the swift jet that breaks through the envelope and produces a gamma-ray burst, but something in between. It moved fast, but not fast enough: about three times slower than typical jets, with an energy below 10⁴⁹ erg. The star strangled it, preventing it from escaping. Thus EP260321a fills the gap between supernova 2008D and faint gamma-ray bursts — now it's clear that dying stars can be even more diverse than previously thought.
The EP260321a flash lasted only seconds, but its X-ray luminosity was billions of times greater than the Sun's total power.
In Carl Sagan's novel 'Contact', an alien signal was disguised as a burst of radiation — astronomers still search for similar short flashes today.