An international team of astronomers led by CHRIST University, Bangalore, found that a massive spiral galaxy almost one billion light-years away from Earth harbours a supermassive black hole billions of times the Sun’s mass which is powering colossal radio jets stretching six million light-years across.

That is one of the largest known for any spiral galaxy and upends conventional wisdom of galaxy evolution, because such powerful jets are almost exclusively found in elliptical galaxies, not spirals.

It also means the Milky Way could potentially create similar energetic jets in the future – with the cosmic rays, gamma rays and X-rays they produce wreaking havoc in our solar system because of increased radiation and the potential to cause a mass extinction on Earth.

A re-think of galaxy evolution

"This discovery is more than just an oddity – it forces us to rethink how galaxies evolve, and how supermassive black holes grow in them and shape their environments," said lead author Professor Joydeep Bagchi, of CHRIST University, Bangalore.

"If a spiral galaxy can not only survive but thrive under such extreme conditions, what does this mean for the future of galaxies like our own Milky Way?

"Could our galaxy one day experience similar high-energy phenomena that will have serious consequences for the survival of precious life in it?"

In the new study, which has been published in Monthly Notices of the Royal Astronomical Society, researchers unravelled the structure and evolution of the spiral galaxy 2MASX J23453268−0449256, which is three times the size of the Milky Way.

Using observations from the Hubble Space Telescope, the Giant Metrewave Radio Telescope, the Atacama Large Millimeter Wave Array and multi-wavelength analyses, they detected an enormous supermassive black hole at its heart and radio jets that are among the largest known for any spiral galaxy, making it a rare phenomenon.

Traditionally, scientists believed that the violent activity of such colossal jets of supermassive black holes would disrupt the delicate structure of a spiral galaxy.

Yet, against all odds, 2MASX J23453268−0449256 has retained its tranquil nature with well-defined spiral arms, a luminous nuclear bar, and an undisturbed stellar ring – all while hosting one of the most extreme black holes ever observed in such a setting.

Adding to the enigma, the galaxy is surrounded by a vast halo of hot, X-ray-emitting gas, providing key insights into its history. While this halo slowly cools over time, the black hole's jets act like a cosmic furnace, preventing new star formation despite the presence of abundant star-making material.

How this compares to Milky Way

Our own Milky Way has a 4 million solar mass black hole – Sagittarius A (Sgr A*) – at its centre, but this is currently in an extremely quiet and dormant state.

That could change if a gas cloud, star, or even a small dwarf galaxy were to be accreted (effectively eaten), the researchers said, potentially triggering significant jet activity. Such events are known as Tidal Disruption Events (TDE) and several have been observed in other galaxies, but not in the Milky Way.

If large jets like this were to emerge from Sgr A*, their impact would depend on their strength, direction, and energy output, the researchers said.

One pointed near our solar system could strip away planetary atmospheres, damage DNA and increase mutation rates because of radiation exposure, while if Earth were exposed to a direct or nearby jet, it could degrade our ozone layer and lead to a mass extinction.

A third possibility is that a powerful jet could alter the interstellar medium and affect star formation in certain regions, which is what has happened in the galaxy the new paper focused on.

Astronomers believe the Milky Way likely had large-scale radio jets in the past and although it could potentially generate them again in the future, experts aren't able to say exactly when because it depends on many factors.

Dark matter clues

The team of researchers also discovered that J23453268−0449256 contains 10 times more dark matter than the Milky Way, which is crucial for stability of its fast spinning disc.

By revealing an unprecedented balance between dark matter, black hole activity, and galactic structure, the experts said their study opens new frontiers in astrophysics and cosmology.

"Understanding these rare galaxies could provide vital clues about the unseen forces governing the universe – including the nature of dark matter, the long-term fate of galaxies, and the origin of life," said co-author Shankar Ray, a PhD student at CHRIST University, Bangalore.

"Ultimately, this study brings us one step closer to unravelling the mysteries of the cosmos, reminding us that the universe still holds surprises beyond our imagination."

ENDS