The discovery, published in the Monthly Notices of the Royal Astronomical Society, highlights significant progress in unraveling the mysteries surrounding GRGs, among the largest structures in the cosmos. Powered by supermassive black holes, these colossal galaxies expel jets of hot plasma that glow at radio frequencies and stretch millions of light-years across intergalactic space.
"The number of GRG discoveries has absolutely exploded in the past five years thanks to powerful new telescopes like MeerKAT," said Kathleen Charlton, a Master's student at the University of Cape Town and lead author of the study. "Research into GRGs is developing so rapidly that it's becoming hard to keep up. It's incredibly exciting!"
Unlike many other GRGs, Inkathazo exhibits unconventional characteristics. "We nicknamed this giant galaxy 'Inkathazo' because it has been a bit troublesome to understand the physics behind what's going on here," Charlton explained. "Its plasma jets have an unusual shape: one of the jets is bent rather than extending straight across."
Adding to the mystery, Inkathazo resides in the dense environment of a galaxy cluster, which would typically inhibit the growth of such massive structures. "Finding a GRG in a cluster environment raises questions about the role of environmental interactions in the formation and evolution of these giant galaxies," said Dr. Kshitij Thorat of the University of Pretoria, a co-author of the study.
To delve deeper into this puzzle, the researchers leveraged MeerKAT's advanced capabilities to create high-resolution spectral age maps. These maps trace the plasma's age across the galaxy, providing insights into the physical processes at play. The analysis revealed unexpected complexities, with some electrons receiving surprising boosts of energy-likely resulting from collisions between the jets and hot intergalactic gas.
"This discovery has given us a unique opportunity to study GRG physics in extraordinary detail," added Thorat. "The findings challenge existing models and suggest that we don't yet fully understand the intricate plasma physics at work in these extreme galaxies."
Inkathazo is not an isolated case. It joins two other GRGs discovered in the COSMOS field, a region of the sky approximately the size of five full moons. These earlier detections were reported in 2021 by the MIGHTEE collaboration, an international team of astronomers observing the southern sky with MeerKAT.
"The fact that we unveiled three GRGs by pointing MeerKAT at a single patch of sky goes to show that there is likely a huge treasure trove of undiscovered GRGs in the southern sky," said Dr. Jacinta Delhaize, a University of Cape Town researcher who led the 2021 publication. "MeerKAT is incredibly powerful and in a perfect location, so is excellently poised to uncover and learn more about them."
As a precursor to the Square Kilometre Array (SKA), which is set to commence operations later this decade, MeerKAT's unparalleled sensitivity and resolution are paving the way for unprecedented discoveries in radio astronomy. "While MeerKAT has taken us further than ever before, the SKA will allow us to push these boundaries even further and hopefully solve some of the mysteries surrounding enigmatic objects like giant radio galaxies," Delhaize concluded.
Research Report:A spatially resolved spectral analysis of giant radio galaxies with MeerKAT
Related Links
MeerKAT International Gigahertz Tiered Extragalactic Exploration
Understanding Time and Space
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