High-Resolution Radio Study Finds Faint Black Hole Activity in Nearby Galaxies

New Delhi– An international team that included an Indian astronomer has used the e-MERLIN radio array to detect compact radio emission from the centers of nearly one-quarter of 280 nearby galaxies, revealing a hidden population of weakly accreting supermassive black holes.

Dr. Aru Beri of the Indian Institute of Astrophysics, an autonomous institution under the Department of Science and Technology, was part of the study, which observed nearby galaxies selected from the Palomar sample and examined their central regions on parsec scales.

The Ministry of Science & Technology said the newly detected weakly accreting supermassive black holes are often missed in conventional observations.

Researchers found compact radio emission from the centers of nearly one-quarter of the galaxies studied, indicating the presence of faintly active supermassive black holes. Most of the detected sources appeared extremely compact, while a smaller fraction showed jet-like radio structures extending over several parsecs.

Scientists said identifying these black holes is important because they can inject energy into their surroundings through jets and outflows, influencing star formation rates and the long-term evolution of galaxies.

Astronomers believe almost every galaxy contains a massive black hole at its center. However, many of these black holes are extremely faint, making them difficult to detect.

The study is among the first statistically complete high-resolution radio surveys capable of isolating faint black hole activity in nearby galaxies. Earlier studies either lacked the sensitivity and angular resolution needed to separate weak nuclear emission from surrounding stellar activity or focused on smaller and potentially biased galaxy samples, the ministry said.

Researchers also used X-ray data from NASA’s Chandra X-ray Observatory to strengthen the findings.

The results suggest that faint, low-level black hole activity may be the dominant mode of black hole growth in the present-day universe. The study also underscores the importance of high-resolution radio observations in revealing weakly active black holes that often remain hidden in conventional galaxy surveys. (Source: IANS)