A mysterious flash of X-rays from deep space that appeared suddenly and vanished within hours has led astronomers to one of the universe’s most powerful cosmic explosions.
An international team led by researchers from the Indian Institute of Astrophysics (IIA) has traced the origin of a rare Fast X-ray Transient (FXT) known as EP241107a, a fleeting burst of X-rays detected on November 7, 2024, by China’s Einstein Probe mission. Their findings provide fresh insights into some of the most violent events in the cosmos and may help solve a long standing astronomical puzzle.
FXTs are among the newest and most enigmatic phenomena discovered in the night sky. These powerful flashes appear without warning, last anywhere from a few minutes to several hours, and then disappear. Because of their short-lived nature, astronomers have struggled for years to determine what causes them.
To investigate EP241107a, scientists launched a global observing campaign using some of the world’s most-advanced telescopes. The breakthrough came when the team identified a radio counterpart to the X-ray flash using the Karl G. Jansky Very Large Array in New Mexico, providing a crucial clue about the event’s origin.
Researchers also relied on several major Indian facilities, including the Himalayan Chandra Telescope and the GROWTH India Telescope in Ladakh, along with the Upgraded Giant Metrewave Radio Telescope.
Additional observations were carried out using the Keck Observatory in Hawaii and the Southern Astrophysical Research Telescope in Chile.
After analysing the optical and radio data and studying the galaxy that hosted the event, the team concluded that EP241107a was most likely linked to a gamma ray burst like explosion, either the collapse of a massive star or the merger of two neutron stars.
The findings suggest that the explosion launched an extraordinarily powerful jet of matter and energy. According to the researchers, the jet carried kinetic energy comparable to the total energy emitted by all the stars in the Milky Way over several months.
What makes the discovery particularly intriguing is that no gamma rays were directly detected from the event. Yet, its afterglow strongly points to a gamma-ray burst origin, making EP241107a one of the clearest examples of what astronomers call an “orphan afterglow", the lingering signature of a cosmic explosion whose initial gamma ray flash went unseen.
The researchers believe the event may represent a previously overlooked, lower energy member of the gamma ray burst family, opening a new window into understanding how these colossal explosions occur across the universe.
The study has been published in the Monthly Notices of the Royal Astronomical Society and involved researchers from the Indian Institute of Astrophysics, IIT Bombay, the California Institute of Technology, the University of North Carolina at Chapel Hill, and the Center for Astrophysics, Harvard & Smithsonian.
