Chennai/Bengaluru, Oct 24 – A significant investigation by astronomers at the Indian Institute of Astrophysics (IIA) has established that activities surrounding supermassive black holes can inhibit the formation of new stars within their host galaxies.

The IIA, based in Bengaluru and operating under the Department of Science and Technology (DST), has its roots in an observatory established in 1786 in Madras, which relocated to Kodaikanal in 1899.

Professor C S Stalin, a faculty member at IIA and co-author of the study, highlighted that advancements in observational astronomy have facilitated this research. He stated, “Due to improvements in instrumentation, such as integral field spectroscopy, we can now examine regions on very small scales that were previously unresolvable with conventional imaging techniques. These observations enable us to explore the intricate relationship between active galactic nuclei (AGN) and their host galaxies.”

Active galactic nuclei are energetic centers of galaxies that emit substantial radiation and, in some instances, powerful relativistic jets, fueled by matter falling onto supermassive black holes that are millions of times more massive than the Sun.

Lead author Payel Nandi, a Ph.D. student at IIA, confirmed that their research demonstrated how intense radiation from black holes and high-speed jets can expel gas from the centers of galaxies, potentially halting star formation in those regions and regulating galactic growth.

Nandi noted the uniqueness of their study, emphasizing its scale and depth, as prior research primarily focused on individual galaxies or smaller samples. “We analyzed 538 AGN and conducted a systematic comparison of optical and radio properties, uncovering trends that link black hole activity, gas outflows, and star formation suppression,” she stated.

The research team integrated optical data from the Sloan Digital Sky Survey (SDSS) with radio data from the Very Large Array (VLA), both located in the United States. The analysis and data cross-matching took nearly four months, culminating in the publication of their findings in ‘The Astrophysical Journal.’

Nandi remarked on the significance of their work for future studies, as it addresses one of astronomy’s major mysteries: why some galaxies cease star formation while others continue to thrive. The findings indicate that to fully comprehend galaxy evolution, astronomers must utilize data across multiple wavelengths—optical, radio, and beyond.

“This approach reveals not only visible light but also the hidden forces and energetic processes that dictate the life cycles of galaxies. Such insights are vital for enhancing theoretical models and computer simulations of galaxy evolution,” she added.

The study’s key takeaway is that radiation from black holes serves as the primary driver of energetic gas outflows. Professor Stalin noted that these outflows, characterized by high-speed streams of gas expelled from galactic centers, are more than twice as prevalent in galaxies detected in radio wavelengths (56 percent) compared to those without radio emissions (25 percent).

Stalin emphasized that this research provides a crucial piece of the puzzle for astronomers seeking to understand the complete picture of galaxy evolution. Nandi concluded that this comprehensive, data-driven study establishes a robust foundation for future investigations into how black holes shape the cosmic landscape.