Christ University and University of Pretoria collaborate to study sizes of galaxies

Bengaluru: Researchers from the University of Pretoria, South Africa and Christ University, Bengaluru use supercomputers to answer why some galaxies grow to immense sizes while others remain small. 

The work was done by an international team, led by Gourab Giri (University of Pretoria) and Prof Joydeep Bagchi (Christ University, Bangalore). The team includes researchers from the University of Pretoria the University of Cape Town in South Africa and the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in India. 

Prof Bagchi initiated the project and helped develop theoretical models, based on his observations. The study found that Giant Radio Galaxies (GRGs) expand due to their high speeds and the low-density environments they exist in.

The research explains how spinning supermassive black holes at the GRGs, power jets of superhot gases that travel near the speed of light. Over millions of years, these jets carve out massive structures that can extend up to 16 million light-years almost nine times the distance between the Milky Way and Andromeda.

As these energetic jets travel through intergalactic space, they transport magnetic fields and high-energy particles (cosmic rays) over vast distances, potentially influencing cosmic magnetism—one of the least understood forces in astrophysics.

Their findings show that the jets not only drive galaxy growth but also play a crucial role in shaping the universe's magnetic fields and influencing galaxy formation, including our Milky Way. "If a powerful radio jet were to pass too close to a developing planetary system, it could strip away atmospheres or expose planets to intense radiation, making them uninhabitable," Prof Bagchi explained.

These discoveries have been made possible through the research team’s dedicated observations using next-generation radio telescopes, including South Africa’s MeerKAT and India’s GMRT, which detect even the faintest remnants of these colossal structures.

Giri, the study’s lead author, emphasised the role of cutting-edge Magneto-Hydro-Dynamical (MHD) simulations running on high-performance machines. “This research combines deep radio observations with state-of-the-art computational simulations, advancing our understanding of the universe’s large-scale structure and the role of colossal black hole jets in galaxy evolution,” he says.