Cosmic Architects: How Supermassive Black Holes Control Galaxy Growth by Halting Star Formation

Meta Description: New research reveals how supermassive black holes and their powerful jets regulate galaxy growth by suppressing star formation, ejecting cosmic gas and 

 

BENGALURU: A groundbreaking new study, spearheaded by astronomers from the Indian Institute of Astrophysics (IIA), has shed light on a crucial cosmic phenomenon: how supermassive black holes and the powerful jets they emit work in tandem to regulate galaxy growth.

The research reveals a fascinating mechanism where these colossal entities actively suppress star formation, effectively shaping the evolutionary path of galaxies across the universe.

The Black Hole’s Role in Halting Star Formation

Published in The Astrophysical Journal, the study demonstrates that both the intense radiation surrounding black holes and their high-speed jets play a significant role. They are capable of ejecting vast amounts of gas from the central regions of galaxies.

This expulsion of gas is vital because gas is the fundamental building block for new stars. By removing this essential material, black holes prevent new stars from forming, offering a compelling explanation for why some galaxies exhibit remarkably low star-formation rates.

Radiation vs. Jets: The Dual Impact

The research team utilized extensive data from the Sloan Digital Sky Survey (SDSS) and the Very Large Array (VLA) in the United States. They meticulously examined over 500 nearby galaxies, each harboring active galactic nuclei (AGN).

AGNs are energetic galactic centers, powered by matter spiraling into supermassive black holes. Understanding their behavior is key to comprehending galaxy evolution.

Payel Nandi, a PhD student at IIA and the study’s lead author, explained, “We found that outflows of warm ionized gas are widespread in AGN. While radiation from the black hole is the main driver, galaxies with radio jets show significantly faster and more energetic outflows.”

Evidence from Cosmic Data

The findings underscore the widespread nature of these gas outflows. They are a critical component in the intricate dance between black holes and their host galaxies.

The Power of Radio Jets

A striking discovery from the study highlights the amplified effect of radio jets. The team found that gas outflows are more than twice as common in galaxies detected at radio wavelengths (56%) compared to those without radio emission (25%).

Speed and Prevalence of Outflows

These powerful outflows can reach astonishing speeds, up to 2,000 kilometers per second. This velocity is more than sufficient to allow the gas to escape the galaxy’s gravitational pull entirely.

CS Stalin, a faculty member at IIA and co-author, emphasized the importance of this multi-wavelength approach. “The study highlights the importance of combining multi-wavelength data to understand the full picture of galaxy evolution,” he stated.

The researchers also observed a strong correlation between the power of these outflows and the total luminosity of the supermassive black holes. Intriguingly, in galaxies featuring radio jets, this link becomes even stronger.

This suggests that radio jets act as “boosters,” significantly enhancing the black hole’s ability to eject gas and influence its surroundings.

Negative AGN Feedback: A Key Mechanism

The results strongly support the concept of “negative AGN feedback.” This is a crucial idea in astrophysics where the activity of a black hole actively suppresses star formation.

It achieves this by blowing away the very gas that is necessary for the creation of new stars, thereby acting as a cosmic regulator.

Key findings from the study include:

• Both radiation and high-speed jets from black holes eject gas.
• Gas outflows are more than twice as common in radio-emitting galaxies.
• Outflows can reach speeds of up to 2,000 km/s, escaping galactic gravity.
• Radio jets act as “boosters,” enhancing gas ejection.
• This process, known as “negative AGN feedback,” suppresses star formation.

Implications for Galaxy Evolution

Understanding these complex interactions is fundamental to comprehending how galaxies grow and evolve over billions of years. KThe interplay between supermassive black holes and their environments dictates much of a galaxy’s life cycle.

Conclusion

This new research from the IIA provides compelling evidence for the intricate relationship between supermassive black holes, their energetic jets, and the overall evolution of galaxies. By acting as cosmic architects, these powerful objects play a critical role in determining which galaxies flourish with new stars and which remain quiescent.

As Dhruba J Saikia, co-author from the Inter-University Centre for Astronomy and Astrophysics (IUCAA), concluded, “This study is a step forward in understanding the complex links between supermassive black holes, jets, star formation and galaxy evolution.” It opens new avenues for future astronomical exploration.