From her first-floor desk at Midnapore City College, astronomer Shobha Kumari has traced events unfolding around a supermassive black hole at the heart of a colossal galaxy nearly two billion light years away — uncovering evidence of a renewed outburst after a long period of relative calm.
Using radio observations from telescopes in Pune and the Netherlands, Kumari detected a rare revival of jets powered by the black hole. These jets were bent, distorted and reshaped as they plough through gas surrounding the cluster of galaxies.
The UK’s Royal Astronomical Society has said the study by Kumari, her supervisor Sabyasachi Pal and two collaborators, could provide fresh insights into how black holes switch between active and quiet phases, and how cosmic environments influence the structure and evolution of galaxies.
The team examined radio emissions from a galaxy catalogued as J1007+3540, mapping it to a staggering size of about 4.7 million light-years across — nearly 50 times larger than the Milky Way.
Their research, published in the journal Monthly Notices of the Royal Astronomical Society, also found evidence that the black hole was “quiet” for about 100 million years before its renewed activity unleashed a fresh set of emissions known as jets.
“It’s like watching a cosmic volcano roar back after ages of calm,” Kumari told The Telegraph. “As the supermassive black hole at the centre of the galaxy begins feeding again, it creates renewed jets that cut through the fading remnants of earlier outbursts.”
Black holes are regions of space where gravity is so intense that not even light can escape. Over cosmic time, some grow into supermassive objects at the centres of galaxies. When gas swirls around these giants, part of it is flung outward in the form of powerful, high-speed jets.
What makes J1007+3540 unusual, Pal explained, is the shape of its radio emissions. “Typically, we see narrow, tightly focused jets streaming in opposite directions,” he said. “Here, instead, we observe a long, faint tail and wispy, spread-out emissions. This is the outcome of a struggle — a battle between the jets and the gas in the cluster of galaxies.”
Astronomers have previously found supergiant galaxies, those with signs of revived jet activity, as well as others where jets are bent and moulded by dense gas that surrounds a cluster of galaxies bound by gravitation, like cosmic neighbours. “But this is the first time we’ve observed all three features together in a single system,” Pal said.
The galaxy J1007+3540 lies embedded in a cluster of roughly 30 galaxies. Radio patterns suggest that while it is actively spewing jets, those jets are being shaped by the cluster gas.
Kumari’s journey into radio astronomy began during her postgraduate studies, when Pal introduced her to the search for a rare class of objects known as hybrid radio galaxies. At the time, only about 30 such galaxies were known. Her work helped push that number beyond 60.
As a research scholar at Midnapore City College, she continued trawling through radio data, identifying galaxies with unusual shapes and behaviours. Her contributions span catalogues of winged, head-tail, and giant radio galaxies, using data from observatories in India, the Netherlands, and the US.
That persistence has now culminated in a discovery astronomers said could sharpen understanding of how black holes flicker between dormancy and violence — and how their surroundings can bend even jets travelling at near light speed.
The study’s collaborators include Surajit Paul of the Manipal Centre for Natural Sciences and Marek Jamrozy of Jagiellonian University in Poland.
The research drew on observations from India’s Giant Metrewave Radio Telescope near Pune and the Low Frequency Array in the Netherlands.
Next, Kumari and Pal plan to probe the galaxy’s core with higher-resolution observations, hoping to glimpse in finer detail how the newly awakened jets carve their way through the surrounding cosmic gas.