Astronomers Detect Rare Black Hole Feeding Event: White Dwarf Torn Apart
Astronomers have reported an exceptionally high-energy cosmic event that may represent a rare form of black hole feeding. The transient phenomenon, designated EP250702a, was first detected in July 2025 by the Einstein Probe mission and subsequently observed by multiple other space telescopes.
Unusual Characteristics of the Event
The brightness of EP250702a rose rapidly in X-rays, produced intense gamma ray flares, and then declined much more quickly than most known tidal disruption events. Researchers propose that the signal is consistent with a white dwarf being torn apart by an intermediate-mass black hole. Such events have been theoretically predicted for years but have not been clearly confirmed until now.
The observations include rapid variability, extreme luminosity, and later spectral softening that does not match previously catalogued transients. These findings offer potential evidence for a long-suspected class of black holes that has remained elusive to astronomers.
Fast X-ray Transient Points to White Dwarf Disruption
The first signs of activity appeared in X-ray data, with emission emerging approximately one day before the strongest gamma ray bursts were recorded. The Einstein Probe identified the source, and follow-up detections came from the Fermi Gamma-ray Space Telescope and other monitoring instruments.
The peak X-ray brightness lasted roughly a single day. Following this peak, the signal dropped sharply over the next couple of weeks. In total, the flux decrease spanned several orders of magnitude within a short timeframe. Most tidal disruption events involving normal stars fade over months or years, but this event did not follow that pattern.
The energy output was particularly striking. Gamma ray flares persisted for hundreds of seconds and suggested that material was being expelled at extremely high velocities, approaching relativistic speeds.
White Dwarf Disruption Explains the Short Timescale
Researchers argue that the fast evolution points to the destruction of a white dwarf rather than a typical star. A white dwarf represents the compact core left behind after a low or medium mass star exhausts its nuclear fuel. It is exceptionally dense and relatively small, closer in size to Earth than to our Sun.
Because of that extreme density, only specific black holes can disrupt it effectively. If the black hole is too massive, the white dwarf would disappear beyond the event horizon before being torn apart. Theoretical models demonstrate that intermediate-mass black holes are precisely the right size to produce this kind of dramatic flare.
This class of black hole occupies the middle ground between stellar mass black holes and the supermassive black holes found at galactic centers. Evidence for their existence has been limited until now. Events like EP250702a may offer one of the clearer pathways to identifying and studying these mysterious cosmic objects.
The Relativistic Jet Adds to the Evidence
In the study titled A fast powerful X-ray transient from possible tidal disruption of a white dwarf, data indicate that a relativistic jet was launched during the event. This means some of the disrupted material was accelerated outward at velocities approaching the speed of light. The hard X-ray and gamma-ray emissions perfectly fit this theoretical picture.
Later observations revealed that the X-ray spectrum became softer. This spectral evolution is consistent with the formation of an accretion disk, where remaining debris circles the black hole and radiates thermal energy. The sequence, progressing from hard energetic flares to softer thermal emission, aligns precisely with theoretical expectations for a white dwarf tidal disruption event.
Other potential explanations were carefully considered by the research team. Scenarios involving smaller black holes or unusual stellar interactions failed to fully reproduce the observed timing, brightness, and spectral changes that characterized EP250702a.
Event May Help Locate Elusive Black Holes
If the current interpretation holds true, EP250702a would represent the first clear jetted tidal disruption of a white dwarf by an intermediate-mass black hole. This discovery would carry significant implications extending far beyond this single cosmic flare.
Intermediate-mass black holes are thought to play a crucial role in the growth and evolution of supermassive black holes. Yet they have remained extraordinarily difficult to detect directly. Transient events like EP250702a may serve as valuable signposts for locating these hidden cosmic objects.
There is also considerable scientific interest in gravitational waves associated with such events. A white dwarf being torn apart could potentially produce both electromagnetic radiation and ripples in spacetime detectable by future instruments like advanced gravitational wave observatories.
For the present moment, EP250702a stands as a remarkable cosmic outlier—bright, brief, and initially difficult to classify. It may ultimately prove to be a missing piece in the larger scientific narrative of how black holes feed, grow, and influence their cosmic environments throughout the universe.
