Something unusual happened 10 billion years ago in a galaxy far from our own. A massive star, dozens of times larger than our sun, made a fatal miscalculation. It ventured too close to a gravitational monster lurking at its galaxy’s heart. What followed was one of the most powerful explosions of light ever witnessed by astronomers, a cosmic violence so extreme that it challenges our understanding of what black holes can do.

In 2018, astronomers at California’s Palomar Observatory detected a mysterious brightening in a distant star. At first, nothing about it seemed unusual. Scientists cataloged it, recorded its brightness, and moved on to other observations. But over the following years, as that light continued to pulse and fade, researchers began to realize they had stumbled upon something extraordinary. Five years would pass before they understood the true scale of what they were observing.

A Cosmic Feast 10 Billion Light-Years Away

Astronomers using the Zwicky Transient Facility eventually identified the source as an active galactic nucleus designated J2245+3743. At its center sits a supermassive black hole weighing 500 million times more than our sun. Distance measurements place this monster almost incomprehensibly 10 billion light-years from Earth, meaning the light reaching our telescopes today began its journey when the universe was just a fraction of its current age.

Scientists nicknamed the event “Superman” for its extraordinary power output. At its peak, the flare blazed with the brightness of 10 trillion suns. Over several months in 2018, astronomers watched the object brighten by a factor of 40, then slowly begin its descent back toward normal levels.

Matthew Graham, who leads the research team at the California Institute of Technology and works as a project scientist for the Zwicky Transient Facility, captured the uniqueness of the discovery when he noted, “This is unlike any AGN we’ve ever seen.” Active galactic nuclei, or AGNs, represent some of the brightest objects in the universe. Gas and dust spiral around their central black holes in flattened disks, heating to extreme temperatures and emitting powerful radiation. Yet even among these cosmic lighthouses, J2245+3743 stands apart.

When a Star Wanders Too Close

Scientists determined that Superman represents a tidal disruption event, or TDE. Such events occur when a star strays into the gravitational kill zone surrounding a supermassive black hole. Gravity’s pull becomes so intense that it literally tears the star apart, stretching it like taffy in a process astronomers call spaghettification. As stellar material spirals into the black hole, it releases tremendous energy in the form of light and radiation.

But J2245+3743 involves no ordinary star. Researchers calculated that the doomed object possessed at least 30 times the mass of our sun before its destruction began. Stars of this size are exceptionally rare in normal galactic environments. Yet evidence suggests they can grow to such enormous proportions within the gas-rich disks surrounding supermassive black holes, where abundant material allows them to bulk up far beyond typical stellar masses.

Before Superman, the most powerful known TDE was an event nicknamed “Scary Barbie” after its technical designation ZTF20abrbeie. Scary Barbie involved a star just three to 10 times the mass of our sun. Superman dwarfs that earlier record holder, both in the mass of its victim and the energy released during the consumption process.

Energy Beyond Comprehension

To grasp the power output of Superman requires wrestling with numbers that defy everyday intuition. K. E. Saavik Ford, an astronomer with the City University of New York and the American Museum of Natural History, offered a striking comparison when she explained, “If you convert our entire sun to energy, using Albert Einstein’s famous formula E = mc^2, that’s how much energy has been pouring out from this flare since we began observing it.”

Measurements indicate that Superman has released approximately 10^54 ergs of ultraviolet and optical energy to date. For context, that represents the complete conversion of roughly one solar mass into pure electromagnetic radiation. Few physical processes in the universe can liberate such staggering amounts of energy.

Superman outshines the previous TDE record holder by a factor of 30. Very few astronomical events approach this level of power output. Even supernovae, the explosive deaths of massive stars, fall short of explaining such extreme brightness. Researchers considered and ruled out alternative explanations, including gravitational lensing effects and supernova explosions within the black hole’s accretion disk, before confirming the tidal disruption scenario.

A Slow-Motion Catastrophe

Observers continue to monitor Superman as it fades, and that ongoing nature tells researchers something important about what’s happening near J2245+3743. Graham offered a vivid description of the star’s predicament, comparing it to “a fish only halfway down the whale’s gullet.” In other words, the black hole hasn’t finished swallowing its meal. Material from the disrupted star continues to spiral inward, releasing energy as it goes.

An unusual aspect of studying Superman involves the way time itself behaves near supermassive black holes. Einstein’s general relativity predicts that time runs slower in strong gravitational fields, an effect called gravitational time dilation. When combined with cosmological effects from the expansion of space, this phenomenon means that seven years of observations here on Earth correspond to just two years of actual time at the location of J2245+3743.

Astronomers are essentially watching the destruction play back at quarter speed, like a slow-motion replay of cosmic violence. Light waves stretch as they traverse the expanding universe, extending their wavelengths and effectively slowing down the apparent timeline of events. For researchers studying black hole physics, this time dilation effect turns out to be a gift. It allows long-term surveys like the Zwicky Transient Facility to capture and analyze events that would otherwise evolve too quickly to study in detail.

Five Years to Reveal Its True Nature

When Superman first appeared in telescope data from November 2018, nothing immediately suggested its extraordinary nature. Astronomers initially thought they might be observing a blazar, a type of black hole that launches energetic jets of material straight toward Earth. Blazars can appear exceptionally bright, but their brightness comes from the orientation of those jets rather than from intrinsic power output.

Superman sat in archival data for five years before researchers took a closer look. In 2023, scientists used the W. M. Keck Observatory in Hawaii to capture detailed spectra of the object. Those measurements revealed that Superman was far more luminous and energetic than anyone had realized. Follow-up observations confirmed that energy was escaping in all directions rather than being beamed toward Earth, ruling out the blazar hypothesis.

Additional data from NASA’s retired Wide-field Infrared Survey Explorer helped establish that Superman’s brightness was genuine rather than artificially magnified by gravitational lensing. Researchers also eliminated massive supernova explosions as potential causes. Supernovae simply cannot account for the sustained, extreme brightness observed in this case.

Hidden Giants at Galactic Centers

Superman belongs to an extremely rare category of events. Roughly 1 in 10,000 active galactic nuclei show any sort of flaring activity, but Superman’s power places it in a class occupied by perhaps 1 in a million AGNs. Its discovery hints at hidden populations of extraordinarily massive stars lurking near the hearts of large galaxies.

K. E. Saavik Ford explained that stars can grow to unusual sizes within AGN accretion disks. Material from the disk gets dumped onto nearby stars, causing them to swell far beyond the masses typically seen in normal stellar environments. Such massive stars would be rare, but the discovery of Superman suggests they exist in greater numbers than previously thought.

Around 100 tidal disruption events have been detected to date, and most have not occurred in active galactic nuclei. Part of the reason is observational. Active black holes constantly produce light as they feed on their accretion disks, and this background glow can camouflage the signatures of individual TDEs. Spotting a tidal disruption against that backdrop resembles trying to notice a camera flash at noon, whereas TDEs around quiet, non-feeding black holes stand out like searchlights in the dark.

Superman’s exceptional brightness overcame this observational challenge. Its flare was so powerful that it easily exceeded the normal emissions from J2245+3743’s accretion disk, making it conspicuous despite the noisy background.

What It Means for Understanding Galaxies

Beyond its record-breaking energy output, Superman offers scientists a window into galactic evolution during the universe’s youth. Because the light has taken 10 billion years to reach Earth, astronomers are observing J2245+3743 as it existed when the universe was less than 4 billion years old. At that epoch, galaxies were still assembling themselves, and star formation rates were higher than they are today.

Understanding what types of stars existed in galactic centers during that early era provides clues about how galaxies grew and evolved. Ford noted that learning about stellar populations at galactic cores gives researchers a new way to investigate galaxy assembly processes across cosmic time.

Superman also challenges the notion that supermassive black holes are simple passive sinks surrounded by orderly disks of material. Instead, the discovery points to complicated, messy environments where massive stars form, evolve, and occasionally meet catastrophic ends. Black holes shape their surrounding environments through powerful radiation and gravitational forces, while simultaneously being shaped by the complex astrophysics of those same environments.

Researchers plan to search through existing Zwicky Transient Facility data for similar events. Additionally, the newly completed Vera C. Rubin Observatory in Chile will scan the sky with unprecedented depth and cadence, potentially discovering more examples of these extreme flares. Each new detection will help astronomers understand how common such events really are and what they reveal about conditions near supermassive black holes.

Witnessing the Universe’s Most Violent Forces

Superman forces us to confront the sheer scale of violence possible in our universe. Somewhere across an expanse so vast that light takes 10 billion years to cross it, a star that had grown to immense proportions was torn apart and consumed. Energy equivalent to converting our entire sun into pure radiation poured into space. And we, tiny observers on a small planet orbiting an average star, managed to catch a glimpse of that destruction as it unfolded.

Such discoveries reshape how we understand our place in the cosmos. We live in a universe where black holes millions of times more massive than our sun can shred and devour stars 30 times larger than the one that gives us life. Events of such magnitude occurred when the universe was young, and their light is only now reaching our instruments.

Superman also represents what becomes possible when humans push observational boundaries. Without seven years of patient monitoring by the Zwicky Transient Facility, this event might have been dismissed as an unremarkable brightening. Without sophisticated instruments that can capture spectra from objects billions of light-years away, its true nature would have remained hidden. Each technological advance allows us to peer deeper into the universe’s most extreme physics laboratories, revealing phenomena that exist at the very edge of what nature permits.

Perhaps most humbling is the realization that Superman is likely not alone. Similar events may be occurring throughout the universe, their light racing toward us through expanding space. Some may already appear in archived data, waiting for patient astronomers to recognize their significance. Others will be spotted by future surveys, adding to our catalog of the universe’s most powerful phenomena. Each discovery teaches us something new about the violent, energetic, and occasionally beautiful processes that govern cosmic evolution across billions of years.

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