Pune’s uGMRT Captures Rare Revival of Dormant Black Hole
Pune: Astronomers have discovered that a black hole has “woken up” after remaining silent for nearly 100 million years. This groundbreaking observation was made using powerful radio telescopes, including India’s upgraded Giant Metrewave Radio Telescope (uGMRT) located at Khodad in Pune district. The study was published in the journal Monthly Notices of the Royal Astronomical Society.
Sabyasachi Pal, an associate professor and head of the department of pure and applied sciences at Midnapore City College in West Bengal, along with his doctoral student Shobha Kumari, and scientists from India and Poland, made this significant find. The black hole is located in the radio galaxy J1007+3540, which is more than three million light-years across, making it about 50 times larger than the Milky Way.
Unlike normal galaxies, J1007+3540 exists inside a dense galaxy cluster, an environment filled with extremely hot gas. The gas produces enormous pressure, creating hostile conditions that strongly affect the shape and behavior of the galaxy. By studying radio waves emitted from the galaxy, scientists observed a rare “double-double” jet structure. This phenomenon involves fresh, bright jets of energy emerging from the galaxy’s center inside much older and weaker jets, confirming that the black hole has restarted its activity after a long pause.
“The galaxy is not just growing quietly in space. It is constantly struggling against extreme pressure from its surroundings. What we are seeing is a black hole that has turned back on and is now fighting against the crushing environment of its galaxy cluster,” Pal explained. He added that J1007+3540 is like a natural laboratory that helps understand how black holes switch on and off, and how they influence the evolution of galaxies over millions of years.
Pressure from the surrounding hot gas is bending the newly formed jets sideways, creating curved and distorted shapes. Scientists also found that the galaxy is losing material as it moves through the cluster, leaving behind a faint, ancient trail called a galactic wake.
Shobha, the lead author of the study, said, “The low-frequency images from uGMRT allowed us to clearly see the extended tail and the inner jets at the same time. Data shows clear signs of ageing in different parts of the galaxy, confirming multiple phases of black hole activity.”
“Studies like this help us understand the full life cycle of supermassive black holes. Observing a black hole that has restarted after millions of years gives us vital clues about how galaxies evolve across cosmic time,” said senior scientist Ishwara Chandra from the National Centre for Radio Astrophysics–Tata Institute of Fundamental Research, Pune (NCRA–TIFR) and part of the research team.
The uGMRT, located in Pune district, is one of the world’s most sensitive radio telescopes, capable of detecting faint radio signals from distant cosmic objects. This facility played a crucial role in capturing the detailed images and data that led to this remarkable discovery. The findings not only shed light on the behavior of black holes but also provide valuable insights into the dynamic processes that shape the universe.
