Young black hole defies physics with record-breaking growth

Astronomers have found a black hole in the early universe that seems to be eating far faster than expected. It shines with record-breaking X-rays for its era and may help explain how some black holes ballooned to giant sizes soon after the Big Bang.

The evidence points to growth that outpaces the usual physical limit. The discovery comes from NASA’s Chandra X-ray Observatory, which revealed the extreme behavior of a quasar called RACS J0320-35.

The object sits about 12.8 billion light-years away, so we see it only 920 million years after the universe began. Earlier observations flagged the quasar, but Chandra’s 2023 data show what sets it apart.

Black hole breaks cosmic growth rules

At the quasar’s core is a black hole weighing roughly a billion suns. It produces more X-rays than any other black hole yet observed within the first billion years of cosmic time.

X-rays trace the hottest, most turbulent regions of the swirling gas that feeds a black hole. In this case, the glow is off the charts for such an early epoch.

The research was led by Luca Ighina at the Center for Astrophysics | Harvard & Smithsonian. “It was a bit shocking to see this black hole growing by leaps and bounds,” said Ighina.

The team’s modeling indicates that the black hole is likely growing at about 2.4 times the so-called Eddington limit.

What’s the Eddington limit?

As matter falls toward a black hole, it heats up and radiates. That light pushes back on the inflowing gas. When the inflow becomes strong enough, the outward radiation pressure balances the inward pull of gravity.

Beyond that point, material normally cannot fall in any faster. This balance point is called the Eddington limit. Many black holes grow below it, some may approach it, but this one appears to exceed it.

Black hole growth in the early universe

There are two main ways to form a billion-solar-mass black hole so early. One is to start big. In that picture, a massive, pristine gas cloud collapses directly into a black hole of ten thousand suns or more, then grows steadily.

The other is to start small, from the death of a massive star – tens of suns – and then grow very fast. If RACS J0320-35 has been growing above the Eddington limit for a sustained time, it could have begun in the modest way and still reached a billion suns this quickly.

“By knowing the mass of the black hole and working out how quickly it’s growing, we’re able to work backward to estimate how massive it could have been at birth,” said study co-author Alberto Moretti of INAF-Osservatorio Astronomico di Brera in Italy. “With this calculation, we can now test different ideas on how black holes are born.”

X-ray clues to runaway feeding

Chandra’s X-ray spectrum – the amount of X-rays at different energies – acts like a fingerprint for the physics at the black hole’s edge.

The researchers compared that fingerprint to theoretical models. The best match came from a black hole accreting faster than the Eddington limit.

Data at optical and infrared wavelengths point the same way. Put together, they imply a feeding rate somewhere between 300 and 3,000 suns per year – huge for such a young system.

Clues to early universe giants

We know giant black holes already existed when the universe was less than a billion years old. The nagging question has been how.

“How did the universe create the first generation of black holes?” said co-author Thomas Connor, a scientist at the Center for Astrophysics. “This remains one of the biggest questions in astrophysics and this one object is helping us chase down the answer.”

If super-Eddington growth turns out to be common at early times, it eases the need for foreign, ultra-massive seeds.

Jets add another twist

RACS J0320-35 also launches narrow jets of particles at nearly light speed. Those are uncommon in quasars. Their presence hints that rapid, messy feeding may help set up the magnetic conditions that power jets.

If so, the same factors that let the black hole gorge – thick disks, chaotic inflow, strong fields – might also help switch the jets on. That connection is still a live mystery.

Quasar brighter than its galaxy

A quasar’s brilliance comes from its accretion disk, not the black hole itself. Gas funnels inward, compresses, and heats to millions of degrees. It radiates across the spectrum, from X-rays to visible light.

That glow can outshine the galaxy that hosts it. In RACS J0320-35, the disk appears especially compact and intense, consistent with a feed rate above the standard cap.

Exploration of black hole growth

The next steps include deeper X-ray exposures and broader wavelength coverage to pin down the growth rate and search for changes over time. High-resolution radio imaging could also trace the jets.

Future observatories will probe even earlier epochs, when the first black holes lit up the darkness. Each new data point will test whether RACS J0320-35 is an outlier or a signpost.

A young black hole in a distant quasar appears to be bulking up faster than the textbook limit. That behavior offers a new route to explain billion-sun monsters so early in cosmic history. It also connects to other puzzles, from the birth masses of the first black holes to what triggers powerful jets.

For now, the message is simple: some of the universe’s earliest black holes may have grown not by nibbling, but by gulping – and Chandra has just caught one in the act.

The study is published in The Astrophysical Journal Letters.

Image Credit: Credit: NASA/CXC/SAO/M

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