A distant supermassive black hole has unleashed the brightest flare ever observed, outshining 10 trillion suns as it tears apart a gigantic star. Detected in 2018 by Caltech's Zwicky Transient Facility, the event marks a rare tidal disruption 10 billion light-years away. Astronomers believe this glimpse into the early universe reveals how massive stars meet their end near active galactic nuclei.
In a cosmic spectacle unfolding across billions of light-years, the supermassive black hole known as J2245+3743 has been caught in the act of devouring one of the universe's largest stars. First spotted in 2018 by the Zwicky Transient Facility (ZTF), a sky survey operated at Caltech's Palomar Observatory and funded by the US National Science Foundation, the object initially showed no unusual features. Spectra from the 200-inch Hale Telescope at Palomar confirmed it as an active galactic nucleus (AGN) with a mass 500 million times that of the Sun.
By 2023, the flare had intensified dramatically, brightening by a factor of 40 within months and reaching a peak luminosity 30 times greater than any previously recorded black hole flare. At its height, it emitted light equivalent to 10 trillion suns. Tracked also by the NSF-funded Catalina Real-Time Transient Survey, the event's extreme brightness allowed detection despite the AGN's dense surrounding disk of material, which typically obscures such occurrences.
Researchers, led by Matthew Graham of Caltech, attribute the outburst to a tidal disruption event (TDE), where the black hole's gravity shreds a star wandering too close. The doomed star was at least 30 times the Sun's mass—far larger than the three-to-ten solar masses involved in the previous record TDE, nicknamed Scary Barbie, which was 30 times dimmer. "The energetics show this object is very far away and very bright," Graham said. "This is unlike any AGN we've ever seen."
Lying 10 billion light-years from Earth, the flare offers a window into the young universe, with light stretched by expanding space causing cosmological time dilation. As Graham explained, "Seven years here is two years there. We are watching the event play back at quarter speed." The black hole appears mid-consumption, with the flare still fading slowly, observed via follow-up spectra from the W. M. Keck Observatory in Hawai'i.
Co-author K. E. Saavik Ford of the City University of New York emphasized the flare's authenticity: data from NASA's Wide-field Infrared Survey Explorer ruled out beaming effects, confirming its intrinsic power. "If you convert our entire Sun to energy, using Albert Einstein's famous formula E = mc², that's how much energy has been pouring out from this flare since we began observing it," Ford noted. Unlike supernovae, which cannot match this intensity, the TDE explanation fits best, potentially fueled by the AGN disk allowing stars to grow exceptionally large.
The findings, detailed in a 2025 Nature Astronomy study supported by the NSF, NASA, and others, highlight ZTF's role in detecting rare events. Future surveys like the Vera C. Rubin Observatory may uncover more such cosmic giants.