A supermassive black hole at the heart of a distant galaxy has erupted back to life after lying completely dormant for nearly 100 million years — unleashing colossal jets of magnetized plasma that now stretch almost one million light-years across space. Astronomers who captured the event say it resembles nothing so much as a volcanic eruption, except at a scale that dwarfs anything in our imagination.
The galaxy at the center of the discovery is called J1007+3540, and what scientists have found inside it may be one of the most dramatic examples ever recorded of a black hole switching itself back on — and reshaping the universe around it in the process.
The Universe’s Most Violent Comeback
Most large galaxies harbor a supermassive black hole at their core. The vast majority of them are quiet — their central engines switched off, their surroundings calm. Only a small fraction produce the enormous jets of radio-emitting plasma that make a black hole visible across intergalactic distances.
J1007+3540 belongs to an even rarer category still: a galaxy whose black hole has done this more than once.
Radio images reveal the galaxy locked in a messy, chaotic struggle between the black hole’s newly ignited jets and the crushing pressure of the massive galaxy cluster in which it resides. The images show a compact, bright inner jet — the unmistakable sign of recent awakening — and just outside it, a cocoon of older, faded plasma: the leftover debris from previous eruptions, distorted and squeezed by the hostile environment surrounding it.
This layered structure — new fire burning inside the ruins of old fires — is what makes J1007+3540 so scientifically compelling. The black hole has not simply switched on for the first time. It has switched on, gone dark, and switched on again. Astronomers call this an episodic active galactic nucleus, or episodic AGN.
What the Radio Telescopes Revealed
The discovery was made using two of the world’s most sensitive radio observatories: the Low Frequency Array (LOFAR) — a vast network of radio antennae spread across Europe, anchored in the Netherlands — and India’s upgraded Giant Metrewave Radio Telescope (uGMRT), one of the largest and most capable radio arrays in the world.
Together, these instruments gave astronomers a view of J1007+3540 that no previous survey had achieved. Low-frequency radio light was crucial because ancient jet debris keeps glowing there long after sharper, higher-frequency views fade. LOFAR and India’s upgraded Giant Metrewave Radio Telescope compared younger inner features with dim outer material from earlier activity — exposing structures that older, coarser surveys largely missed, especially the faint tail and compressed northern region.
What they found inside those images was remarkable. A bright inner streak sits inside older, dimmer debris, showing two eruptive episodes. The newer jet had not erased older wreckage, which stayed visible as a fading outer cocoon — that layering preserved earlier history and exposed how the surrounding cluster kept shaping the eruption.
The researchers were also able to date the different layers using radiative age — a technique that measures how long the energetic particles inside the jets have been cooling down. The inner lobes were dated to 140 million years, while the older outer north lobe reached roughly 240 million years — preserving a record of an earlier eruption that outlasted the shutdown. That 100-million-year gap between the layers is the silence — the dormancy — that preceded the current awakening.
The Cosmic Volcano Description
Lead researcher Shobha Kumari of Midnapore City College in India led the international team behind the study. Her description of what they observed has become one of the most vivid summaries in recent astronomy:
“It’s like watching a cosmic volcano erupt again after ages of calm — except this one is big enough to carve out structures stretching nearly a million light-years across space. This dramatic layering of young jets inside older, exhausted lobes is the signature of an episodic AGN — a galaxy whose central engine keeps turning on and off over cosmic timescales.”
For scale: the Milky Way, our own galaxy, is roughly 100,000 light-years across. The structures carved by J1007+3540’s black hole span ten times that distance.
A Battle Between Black Hole and Galaxy Cluster
What makes J1007+3540 especially unusual is not just that its black hole restarted — it is where that black hole lives.
J1007+3540 is situated in a massive galaxy cluster filled with extremely hot gas. This dense environment exerts intense pressure on the newly revived jets, which are twisted and distorted by the surrounding gases. Rather than blasting outward in straight, symmetrical beams, the jets are bent, squeezed, and reshaped by the cluster medium pressing back against them.
The LOFAR image reveals that the northern lobe is compressed and dramatically distorted, showing a curved backflow signature of plasma that seems to be shoved sideways by the surrounding gas.
Co-author Dr. Sabyasachi Pal put it plainly: “J1007+3540 is one of the clearest and most spectacular examples of episodic AGN with jet-cluster interaction, where the surrounding hot gas bends, compresses, and distorts the jets.”
This tug-of-war between the black hole’s enormous outward energy and the cluster’s crushing inward pressure is not just spectacular to observe — it is also scientifically vital. The interaction leaves a record of how these two forces have contested each other over hundreds of millions of years.
Why This Discovery Matters
Beyond the spectacle, the findings carry significant implications for how scientists understand galaxy evolution.
For decades, astronomers assumed that galaxies grow in a relatively continuous, steady way — new stars forming, material slowly accumulating. What discoveries like J1007+3540 reveal is that galactic evolution is often anything but smooth.
The authors say it shows that the growth of galaxies is not peaceful or gradual but rather a battle between the explosive power of black holes and the crushing pressure of the environments they live in.
Every time J1007+3540’s black hole erupts, it pumps enormous amounts of energy into the surrounding cluster gas — heating it, stirring it, and potentially suppressing the formation of new stars across a region millions of light-years wide. Then, when the black hole falls quiet, the gas cools. New material falls back toward the center. And eventually, the cycle begins again.
Systems like J1007+3540 offer valuable clues about how black holes behave over time — how often they switch between active and quiet states, how jets change as they age, and how surrounding environments can alter the structure of entire galaxies.
Niel Brandt, an astrophysicist at Pennsylvania State University who studies similar systems, noted the galaxy’s scientific value: “This system is just physically very large, and that makes it more amenable to study in many ways. You can go in and study it in considerable detail.”
What Comes Next
The research team is not finished with J1007+3540. They now plan to use more sensitive, high-resolution observations to zoom even deeper into the core and track how the restarted jets propagate through this turbulent environment.
Higher-resolution follow-up images could reveal the fine structure of the innermost jets — precisely how the black hole is feeding, and how the energy of the eruption is being transferred into the surrounding cluster. Future observations may also uncover additional layers of past eruptions, extending the galaxy’s known history even further into the past.
Instead of a fully spent galaxy, J1007+3540 seems to hold the ingredients for another restart in the future.
A sleeping giant, not yet finished.
Key Facts at a Glance
| Detail | Data |
|---|---|
| Galaxy | J1007+3540 |
| Black Hole Type | Supermassive (Active Galactic Nucleus) |
| Duration of Dormancy | ~100 million years |
| Size of Eruption | ~1 million light-years |
| Age of Inner Jets | ~140 million years |
| Age of Outer Lobe | ~240 million years |
| Telescopes Used | LOFAR (Netherlands), uGMRT (India) |
| Lead Researcher | Shobha Kumari, Midnapore City College, India |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Published | January 15, 2026 |
Original Journal Source
 Shobha Kumari, Sabyasachi Pal, Surajit Paul, Marek Jamrozy. “Probing AGN duty cycle and cluster-driven morphology in a giant episodic radio galaxy.” Monthly Notices of the Royal Astronomical Society, 2026; 545 (4). 🔗 DOI: 10.1093/mnras/staf2038
Press Release — Royal Astronomical Society: 🔗 ras.ac.uk — Reborn black hole spotted erupting like cosmic volcano
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