The Ministry of Science & Technology announced groundbreaking astronomical research conducted by the Indian Institute of Astrophysics (IIA), an autonomous institution under the Department of Science and Technology. An international team of astronomers, including Dr. Aru Beri from IIA, used the e-MERLIN radio array to conduct high-resolution radio investigations of 280 nearby galaxies selected from the Palomar sample, probing their central regions on parsec scales.
The study detected compact radio emission from the centres of nearly one-quarter (approximately 25%) of the observed galaxies, revealing the presence of weakly accreting supermassive black holes that conventional observations often miss. Most detected sources appeared extremely compact, while a smaller fraction showed jet-like radio structures extending over several parsecs. This represents one of the first statistically complete high-resolution radio surveys capable of isolating faint black hole activity in nearby galaxies.
To confirm their findings, the researchers complemented radio observations with X-ray data from NASA's Chandra X-ray Observatory. The combined observations helped verify that the detected emission is powered by actively accreting supermassive black holes rather than stellar processes such as star formation, supernova remnants, or X-ray binary systems within the galaxies.
The results suggest that faint, low-level black hole activity may represent the dominant mode of black hole growth in the present-day Universe. The study highlights the importance of high-resolution radio observations in revealing a population of weakly active black holes that often remain hidden in conventional galaxy surveys. These black holes can inject energy into their surroundings through jets and outflows, influencing star formation rates and the long-term evolution of galaxies.
The research was published in the Monthly Notices of the Royal Astronomical Society and was authored by D. R. A. Williams-Baldwin and an international team of collaborators, including IIA faculty member Dr. Aru Beri. The study utilized the e-MERLIN radio array consisting of 7 radio telescopes across the UK functioning as an interferometer.
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