Chinese scientists report first likely sighting of black hole devouring white dwarf

(ECNS) - Chinese astronomers said they have likely captured the first direct evidence of a mid-sized black hole ripping apart and consuming a white dwarf star, shedding new light on a long-theorized but rarely observed cosmic process.

The discovery is based on observations of a powerful high-energy space explosion known as EP250702a, detected by China's Einstein Probe satellite, according to the National Astronomical Observatories of the Chinese Academy of Sciences. The findings were published this month in the journal Science Bulletin.

Mid-sized black holes, thought to bridge the gap between stellar-mass and supermassive black holes, are difficult to detect because they produce few observable signals unless actively feeding on nearby matter.

Li Dongyue, a researcher at the observatory, said an early burst of X-rays appeared nearly a day before gamma rays were detected, indicating the source was not a typical gamma-ray burst.

This early X-ray signal shows that the engine had already started operating before the gamma-ray flash, Li said.

Follow-up observations by telescopes worldwide tracked the event for more than a month, revealing that its brightness dropped more than 100,000 times within weeks, a pace far faster than seen in known stellar disruptions.

Zhang Wenda, a deputy researcher at the observatory, said the long-lasting flares and extreme energy output were consistent with rare black hole-driven stellar destruction events involving high-speed jets of matter.

Based on the data, the research team concluded the most likely explanation was a white dwarf - a dense stellar remnant - being torn apart by a mid-sized black hole tens of thousands of times more massive than the sun.

Yuan Weimin, the Einstein Probe's chief scientist, said the unusually fast fading suggested the star involved was far denser than normal, supporting the white dwarf scenario.

Some international scientists have proposed alternative explanations, including mergers involving smaller black holes.

Dai Lixin, a professor at the University of Hong Kong, said the existence of different theories shows the "huge scientific value" of this event. But the white dwarf–black hole model best matched the rapid evolution and extreme energy observed, Dai added.

(By Zhang Jiahao)