Astronomers have discovered the earliest known flickering quasar, whose light has traveled more than 13 billion years to reach us.
It can help reveal how some of the Universe's biggest black holes grew so unexpectedly monstrous so early in cosmic history.
Surprisingly, this ancient quasar, designated J0439+1634, appears to have a pancake-shaped accretion disk of matter swirling into its mammoth maw, suggesting it is mysteriously mature for its age.
"This provides direct evidence that the same feeding processes and structures observed in the nearby Universe were already in place at very early times, despite very different cosmic environments, says Anna-Christina Eilers, an observational astrophysicist at MIT.
"Which had never been seen before."
Quasars are brilliant active galactic cores, powered by supermassive black holes (SMBHs) feeding.
Among the brightest, most energetic objects in the cosmos, quasars beam with a brilliance that outshines entire galaxies containing trillions of suns.
Nearby quasars are known to flicker, as material falls unevenly into their central black holes.
"The flickering comes from fluctuations in the way the gas is being fed into the black hole," explains MIT astronomer Gene Leung.
"And how a quasar flickers tells us something about the structure of a black hole's accretion disk, and the kind of 'bites' that the black hole is eating."
But spotting such flickering in the early Universe is extremely difficult.
In their new study, an international team of astronomers led by MIT has described the earliest object of this type.
The researchers observed this quasar 'blinking' at us across a huge swath of spacetime, as it appeared when the Universe was only 850 million years old, during a period of rampant star formation called the cosmic dawn.
"Although there have been a lot of quasars found in the cosmic dawn, this is the first time we actually see one flickering," says Leung.
Finding and characterizing this flicker, from the 'opposite side' of the cosmos, presented an incredible challenge.
As the Universe expands, it stretches the light arriving at our telescopes into longer, redder wavelengths, through a process known as redshift.
You might experience a similar effect when an approaching ambulance siren's pitch appears higher, then drops lower as the sound moves away from you.
And since space and time are inextricably linked, the stretching of the cosmic fabric also affects time.
From a vantage point billions of light-years away on Earth, a flicker that occurs over weeks can appear to span months.
To detect the signal, astronomers used multi-wavelength data from ground- and space-based observatories, including NASA's Near-Earth Object Wide-field Infrared Survey (NEOWISE), which produced a time-lapse of the entire night sky in infrared from 2010 to 2024.
"We saw the quasar flickering randomly over the 14-year period, much like a candle's flame flickers without a fixed pattern," explains Leung.
By tracking its flux across multiple wavelengths, including infrared and X-ray, the astronomers estimate that this ancient quasar has a mass exceeding 600 million Suns.
Our local SMBH, Sagittarius A*, which resides at the heart of the Milky Way, is a relative lightweight at around 4 million solar masses.
J0439+1634 is also unbelievably bright, glowing with the brilliance of 12 trillion Suns.
Tracking its flux to reveal the temperature and proximity of material falling into its black hole also allowed the astronomers to map its accretion disk.
Curiously, they found that it was flat and relatively ordered, even though early SMBHs are thought to have immature, chaotically "puffy" disks that had not yet settled.
Accordingly, quasars in the nearby Universe have tinier, tidier accretion disks and coronae because they are more mature.
"I think what this suggests is that all the messy, very rapid growth phases that we expect all black holes to go through at some point happen very, very early on, before we see them as these very bright luminous quasars," says Eilers.
This work also offers new methods for measuring the mass of some of the oldest quasars, and constraining the size of the black hole seeds necessary to form SMBHs with billions of solar masses when the Universe was only around 10 percent of its current age.
The researchers now hope to discover even earlier quasars to better study their growth and influence on galactic evolution.
Related: Scientists Discover Giant Black Hole Growing 2.4X Faster Than Theoretical Limit
Fortunately, this study establishes the ground (and space) work to detect them with next-generation facilities, including the recently inaugurated Vera C. Rubin Observatory in Chile and the Nancy Grace Roman Space Telescope, set to launch in August.
The future of quasar research at cosmic dawn appears literally and figuratively brilliant – even if the light being studied began its journey more than 13 billion years ago.
This research was published in Nature Astronomy.