**Executive Summary**
This report details a high-resolution radio survey of 280 nearby galaxies conducted by an international team, including researchers from the Indian Institute of Astrophysics. The study, published on July 6, 2026, reveals a hidden population of weakly active supermassive black holes that influence star formation and galaxy evolution. These findings suggest that faint, low-level activity is the dominant mode of black hole growth in the present-day Universe.
**Key Points / Main Content**
**Study Scope and Methodology**
* Researchers used the e-MERLIN radio array, a seven-telescope interferometer in the UK, to observe 280 galaxies from the Palomar sample.
* The study probed the central regions of these galaxies on parsec scales to isolate faint nuclear emission.
* Radio observations were complemented by X-ray data from NASA’s Chandra X-ray Observatory to confirm that emissions originated from black holes rather than stellar processes like supernovae.
**Major Scientific Findings**
* Compact radio emission was detected in nearly one-quarter of the observed galaxies, revealing weakly accreting supermassive black holes often missed by conventional observations.
* While most detected sources appeared extremely compact, a small fraction exhibited jet-like radio structures extending over several parsecs.
* The research represents one of the first statistically complete high-resolution radio surveys capable of separating weak nuclear activity from surrounding stellar activity.
**Implications for Galactic Evolution**
* Weakly active black holes inject energy into their surroundings through jets and outflows, which affects star formation rates.
* The study highlights that low-level activity may be the primary mechanism for black hole growth in the local Universe.
* High-resolution radio observations are established as a critical tool for uncovering populations of black holes that remain hidden in ordinary galaxy surveys.
**Impact Analysis**
**International Astronomical Community**
**Impact**
The discovery provides a new understanding of how "hidden" black holes influence the long-term evolution of galaxies and star formation.
**Action Required**
Researchers must integrate this data into existing models of galactic evolution and black hole growth modes to account for widespread low-level activity.
**Indian Institute of Astrophysics (IIA) / Department of Science and Technology (DST)**
**Impact**
The involvement of IIA faculty (Dr. Aru Beri) in this international collaboration elevates the institution's profile in the field of high-resolution radio astronomy.
**Action Required**
The institutions should continue to support and facilitate international collaborations and high-resolution surveys to further explore the local Universe.
**Astrophysics Publishers and Journals**
**Impact**
The *Monthly Notices of the Royal Astronomical Society* serves as the primary platform for disseminating these statistically complete survey results to the global scientific community.
**Action Required**
Maintain the publication's availability via the provided digital links to ensure researchers can access the full technical dataset and methodology.
Key Entities Referenced
Indian Institute of Astrophysics (IIA): An autonomous institution under the Department of Science and Technology that participated in the international research team identifying faint black hole activity.
Department of Science and Technology (DST): The primary administrative department of the Indian government that oversees and supports the Indian Institute of Astrophysics (IIA).
e-MERLIN radio array: A network of radio telescopes in the UK functioning as an interferometer, used to conduct the high-resolution radio survey of nearby galaxies.
NASA’s Chandra X-ray Observatory: A space-based observatory used to provide complementary X-ray data that helped confirm the presence of accreting supermassive black holes.
Monthly Notices of the Royal Astronomical Society: The academic journal where the research findings concerning widespread faint black hole activity were published.
Ministry of Science & Technology
High-resolution radio study reveals widespread
faint black hole activity in nearby galaxies
प्रव तथ: 06 JUL 2026 3:56PM by PIB Delhi
High-resolution radio investigations of nearby galaxies have revealed a hidden population of weakly
active black holes in the local Universe that was so far difficult to detect.
Hunting these hidden monsters is essential as they can inject energy into their surroundings through jets
and outflows, influencing star formation rates and the long-term evolution of galaxies.
Astronomers believe that almost every galaxy harbours a massive black hole at its centre. However, many
of these black holes remain extremely faint and spotting them was a challenge.
An international team of astronomers, including Dr. Aru Beri from the Indian Institute of Astrophysics
(IIA), an autonomous institution under the Department of Science and Technology (DST), used the e-
MERLIN radio array, to observed 280 nearby galaxies selected from the Palomar sample and probe their
central regions on parsec scales.
The researchers detected compact radio emission from the centres of nearly one-quarter of the galaxies,
revealing the presence of weakly accreting supermassive black holes that are often missed in conventional
observations. Most detected sources appear extremely compact, while a smaller fraction shows jet-like
radio structures extending over several parsecs.
Fig 1: The locations of the 7 e-MERLIN radio telescopes across the UK, functioning as an interferometer
(Credits: Jodrell Bank, UK)
The study represents one of 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 focusedon smaller and potentially biased galaxy samples. By targeting a large and well-defined sample at very
high radio resolution, the researchers were able to systematically uncover low-level black hole activity in
ordinary nearby galaxies.
To strengthen these findings, the radio observations were complemented with X-ray data from NASA’s
Chandra X-ray Observatory. The combined observations helped confirm that the detected emission is
powered by actively accreting supermassive black holes rather than by 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 also 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.
Fig 2: e-MERLIN images of some radio galaxies
This study 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 Aru Beri, a faculty
member at IIA.
Publication Link: https://academic.oup.com/mnras/article/548/2/stag532/8527739
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