BEIJING -- China's Einstein Probe (EP) satellite has detected a previously unknown type of cosmic explosion involving faint and fast X-ray transients that occur during the death of massive stars.

The discovery, published in the latest issue of the journal Nature Astronomy, challenges existing theories of stellar collapse and reveals a hidden class of stellar explosions.

The satellite spotted a mysterious 150-second X-ray flare, named EP240414a, from a dying star 4 billion light-years away. Follow-up observations confirmed its link to a rare supernova, SN 2024gsa, and revealed a weak relativistic jet, similar to those in gamma-ray bursts (GRBs) but slower and less energetic.

EP's advanced wide-field X-ray vision allowed scientists to track the jet's evolution, providing crucial evidence for understanding both jet formation mechanisms and the underlying physics of supernova explosions.

"These fast X-ray transients are like cosmic fireworks, bright and fleeting, making them extremely challenging to detect," said lead author Gao He from Beijing Normal University. "Past missions missed them due to limited detection capabilities."

"This marks EP's first discovery of an X-ray transient linked to a supernova, heralding a new era in time-domain high-energy astrophysics," added co-corresponding author Wang Xiaofeng of Tsinghua University.

Launched in January 2024, EP uses cutting-edge "lobster-eye" optics to monitor the X-ray sky with unmatched sensitivity.

"EP240414a showcases EP's ability to uncover new cosmic phenomena," said EP's principal investigator, Yuan Weimin, from the National Astronomical Observatories of the Chinese Academy of Sciences.

Scientists expect more breakthroughs as the mission continues to explore the dynamic universe.