MeerKAT spots a troublesome cosmic beast

BY DR JACINTA DELHAIZE (UNIVERSITY OF CAPE TOWN)

South Africa’s MeerKAT telescope has uncovered an extraordinary new giant radio galaxy nicknamed Inkathazo, meaning “trouble” in the African Xhosa and Zulu languages, which sheds light on the evolution of the largest structures in the Universe and offers new, yet confusing, insights into their mysterious origins.

Giant radio galaxies are rare cosmic behemoths spewing jets of hot plasma millions of light years across intergalactic space. These plasma jets, which glow at radio frequencies, are powered by supermassive black holes at the centres of galaxies.

Inkathazo’s plasma jets span 3.3 million light years – over 32 times the size of the Milky Way.

“It has been a bit troublesome to understand the physics behind what’s going on here,” said Kathleen Charlton, a master’s student at the University of Cape Town and the first author of the study.

“It doesn’t have the same characteristics as many other giant radio galaxies. For example, the plasma jets have an unusual shape. Rather than extending straight across from end-to-end, one of the jets is bent.”

Additionally, Inkathazo lives at the very centre of a cluster of galaxies, rather than in relative isolation, which should make it difficult for the plasma jets to grow to such enormous sizes.

Researchers took advantage of MeerKAT’s exceptional capabilities to create some of the highest-resolution spectral age maps ever made for giant radio galaxies. The maps track the age of the plasma across different parts of the galaxy, providing clues about the physical processes at work.

The results reveal intriguing complexities in Inkathazo’s jets, with some electrons receiving unexpected boosts of energy. The researchers believe this may occur when the jets collide with hot gas in the voids between galaxies in a cluster.

The work, co-authored by several members of the international MIGHTEE collaboration, has been published in the Monthly Notices of the Royal Astronomical Society.

The newly discovered giant radio galaxy Inkathazo. The glowing plasma jets, as seen by the MeerKAT telescope, are shown in red and yellow. The starlight from other surrounding galaxies can be seen in the background. The large spiral galaxy seen in the lower-left of centre is actually a much closer foreground galaxy which is unrelated to Inkathazo.

Credit: K.K.L Charlton (UCT), MeerKAT, HSC, CARTA, IDIA.