China’s Einstein Probe has detected an event that astronomers suspect to be the first recorded instance of a black hole devouring a white dwarf, with broad implications for astronomy.
One of the most extreme high-energy events known to occur in the cosmos, the observation was made on July 2, 2025, when astronomers detected a powerful source of rapidly brightening and dimming X-rays during a routine sky survey. From there, a global hunt was on, with telescopes around the world monitoring the event, culminating in a recent paper published in Science Bulletin.
Spying a Cosmic Burst
The EP Science Center of the National Astronomical Observatories, Chinese Academy of Sciences (NAOC), led the work, with an international assembly of scientists participating. From this collaboration, the interpretation of the event as possibly being the final moments of a white dwarf came into focus.
The EP consists of two X-ray instruments, the Wide-field X-ray Telescope (WXT) and the Follow-up X-ray Telescope (FXT), which, as the latter’s name suggests, are designed to work together. With its high sensitivity and wide field of view, WXT was the first to spot the transient X-ray source EP250702a. WXT wasn’t the only one watching this portion of the sky, as NASA’s Fermi Gamma-ray Space Telescope identified a series of gamma-ray bursts occurring in the same region.
Astronomers later discovered that WXT data from the previous day already showed X-ray emission from the same location, occurring before the gamma-ray bursts—an unusual sequence for cosmic explosions. Roughly 15 hours after the initial detection, the source reached peak luminosity, making EP250702a one of the brightest bursts ever observed.
“This early X-ray signal is crucial,” said lead author Dr. Dongyue Li, of the National Astronomical Observatories of China. “It tells us this was not an ordinary gamma-ray burst.”
All Eyes on the Black Hole
WXT data provided a precise location for the emissions, allowing observatories worldwide to gather multi-wavelength observations. Within about 20 days, the object’s brightness dropped by more than a factor of 100,000.
The expanding dataset presented a challenge. Observations across multiple wavelengths did not match existing models. Key features included bright X-ray emission preceding a gamma-ray burst, rapid evolution, and an unusual location near the edge of its host galaxy rather than its center. Researchers concluded that an intermediate-mass black hole tearing apart a white dwarf best explained the unusual combination of observations.
Modeling a Black Hole Consumption
Astrophysicists from the University of Hong Kong contributed key modeling expertise. Professor Lixin Dai advocated for the white dwarf–intermediate-mass black hole interpretation, which proved the best fit to the data.
“The white dwarf–intermediate-mass black hole model can most naturally explain its rapid evolution and extreme energy output,” Dai explained.
“Our computational simulations show that the combination of the tidal forces of an intermediate-mass black hole, combined with the extreme density of a white dwarf, can produce jet energies and evolutionary timescales that are highly consistent with the observational data,” said co-first author Dr. Jinhong Chen, a postdoctoral fellow in the HKU Department of Physics
“Confirmation of the intermediate-mass black holes theory would have a profound impact on our understanding of black hole formation and evolution,” Dr. Chen told The Debrief. “It would bridge the gap between stellar-mass and supermassive black holes, providing crucial insights into the mechanisms that govern black hole growth.”
Continuing to Monitor Black Holes
In an email, Dr. Chen told The Debrief that several specific confirmations would be required to support the paper’s conclusions:
“Observations of tidal disruption events (TDEs), particularly those involving white dwarfs (WDs), which are theorized to be disrupted only by intermediate-mass black holes (IMBHs), would support the theory,” Dr. Chen explained. “The characteristics of these TDEs, such as their luminosity, duration, and spectral properties, should match the predictions of IMBH-WD TDE models.”
“Detailed studies of the host galaxies of suspected IMBH-TDEs could reveal offset or wandering IMBHs, providing additional evidence for their existence,” Dr. Chen continued. “Comprehensive multi-wavelength observations, including X-ray, optical, and radio data, would help constrain the properties of the central engine and confirm the presence of an IMBH.”
Researchers are already conducting follow-up observations. Monitoring of EP250702a and similar X-ray transients continues, while astronomers collect optical and radio data on the event’s afterglow and host galaxy. The team is also refining its simulations to incorporate new observations.
Future capabilities afforded by the development of new cutting-edge instruments may provide decisive evidence. The planned Laser Interferometer Space Antenna (LISA), for instance, could detect gravitational waves produced by white dwarf–IMBH tidal disruption events, while next-generation ground-based observatories such as the Extremely Large Telescope and the Thirty Meter Telescope are expected to reveal new details about host galaxies and their central black holes.
The paper, “A Fast, Powerful X-ray Transient from Possible Tidal Disruption of a White Dwarf,” appeared in Science Bulletin on January 8, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.