J2245+3743 is the most powerful and most distant black‑hole flare recorded, peaking at a luminosity equivalent to about 10 trillion Suns. First seen in 2018, the event brightened ~40× over months and is best explained as a tidal disruption event in which a ~30‑solar‑mass star was torn apart by a ~500‑million‑solar‑mass black hole. By March 2025 the source had emitted ~1054 erg and remained ≈2 magnitudes above its pre‑flare level. Cosmological time dilation stretches the observed timeline, making the event appear to us at roughly quarter speed.
Most Powerful and Distant Black‑Hole Flare Ever Seen — As Bright as 10 Trillion Suns
J2245+3743 is the most powerful and most distant black‑hole flare recorded, peaking at a luminosity equivalent to about 10 trillion Suns. First seen in 2018, the event brightened ~40× over months and is best explained as a tidal disruption event in which a ~30‑solar‑mass star was torn apart by a ~500‑million‑solar‑mass black hole. By March 2025 the source had emitted ~1054 erg and remained ≈2 magnitudes above its pre‑flare level. Cosmological time dilation stretches the observed timeline, making the event appear to us at roughly quarter speed.
19:28, 05.11.2025Science
Most powerful and distant black‑hole flare ever recorded
A flare whose light has traveled roughly 10 billion years to reach Earth is now the most powerful and most distant black‑hole eruption astronomers have observed. The outburst, from a source labeled J2245+3743, reached a peak luminosity equivalent to about 10 trillion Suns.
A team led by Caltech astrophysicist Matthew Graham concludes the burst was probably caused by a supermassive black hole — roughly 500 million times the mass of the Sun — shredding a star that wandered too close to the galactic center. Such catastrophic encounters are called tidal disruption events (TDEs).
"The energetics show this object is very far away and very bright. This is unlike any AGN [active galactic nucleus] we've ever seen," Graham says.
The source brightened dramatically in 2018, increasing in brightness by about a factor of 40 over a few months and climbing to a peak roughly 30 times brighter than the previous strongest AGN flare — an event nicknamed "Scary Barbie." Since that peak the object has slowly faded but remains significantly brighter than its pre‑flare level.
By the time the team submitted their paper in March 2025, the total radiated energy was estimated near 1054 erg, an amount comparable to converting the Sun’s entire mass into electromagnetic radiation.
Why the team favors a TDE
Several cosmic phenomena can produce sudden, slowly fading flashes — for example, the BOAT (Brightest Of All Time) gamma‑ray burst tied to a supernova, kilonovae from neutron‑star mergers, or intrinsic variability in active galactic nuclei. Each produces characteristic light curves and spectra.
After modeling J2245+3743's evolving light, Graham and colleagues found the signal best matches a TDE. Their analysis suggests the disrupted star was unusually massive — around 30 solar masses — torn apart by the black hole’s tidal forces and forming a luminous accretion disk as debris fell inward.
"Stars this massive are rare, but we think stars within the disk of an AGN can grow larger. The matter from the disk is dumped onto stars, causing them to grow in mass," says K. E. Saavik Ford of the City University of New York.
The disk formed from the torn star likely powered the extreme brightness. As the black hole continues to consume the debris, J2245+3743 remains about two magnitudes brighter than before the flare; the source is expected to return to baseline only after the last fragments cross the event horizon.
Cosmological time dilation — watching the event in slow motion
An important observational effect makes the eruption appear stretched in time: cosmological time dilation caused by the expansion of the Universe. Because the light traveled across expanding space, the observed timeline runs more slowly than the event did at the source.
"It's a phenomenon called cosmological time dilation due to stretching of space and time. Seven years here is two years there. We are watching the event play back at quarter speed," Graham says.
Accounting for time dilation is essential to reconstruct the TDE's true timeline and the physical processes that govern how debris falls back onto the black hole. The authors note that applying these lessons to archival surveys and reexamining misclassified transients could reveal additional extreme TDEs.
Publication: The full study is published in Nature Astronomy.