Scientists from the University of Cape Town (UCT), using South Africa’s MeerKAT radio telescope array in the Karoo, have discovered a rare giant radio galaxy (GRG). They have named it “Inkathazo”, and their discovery was published in the Monthly Notices of the Royal Astronomical Society on Monday (January 20).

“[GRGs] are extraordinary cosmic phenomena — massive galaxies emitting plasma jets millions of light-years across intergalactic space, powered by supermassive black holes at their centres,” explained UCT. “While previously considered rare, a surge of GRG discoveries has been made possible by cutting-edge telescopes like MeerKAT, transforming the understanding of these cosmic behemoths.”

The setting up of MeerKAT, and other powerful new telescopes, has resulted in the discovery of rapidly increasing numbers of GRGs. It is a sector of astronomical and astrophysical research that is growing rapidly.

Inkathazo is unusual in that it has plasma jets that extend across 3.3-million light years, which is more than 32 times the size of our own galaxy, the Milky Way.

“It doesn’t have the same characteristics as many other giant radio galaxies,” reported study first author and UCT Master’s student Kathleen Charlton. “For example, the plasma jets have an unusual shape. Rather than extending straight across from end-to-end, one of the jets is bent.”

These, and other peculiar physics displayed by Inkathazo, which are posing challenges to scientists, were the reason for its name. In both the Zulu and Xhosa languages, Inkathazo means “trouble”.

“The researchers used MeerKAT’s advanced capabilities to create high-resolution spectral age maps of Inkathazo, which track the age of the plasma jets across different regions,” elucidated Charlton. “These maps revealed unexpected energy boosts in the electrons within the jets, likely caused by collisions with hot gas between galaxies in the cluster. This discovery challenges existing plasma physics models and highlights the complexities of these extreme cosmic objects.”

This is the third GRG discovered by MeerKAT, all located within the same part of the sky. This suggests that there are many more GRGs to be discovered in the southern hemisphere sky.

MeerKAT is operated by the South African Radio Astronomy Observatory. It is also serving as a precursor for the international Square Kilometre Array (SKA) radio telescope, the mid-frequency array of which will be co-located with the MeerKAT. In due course, MeerKAT would be absorbed into the SKA.

“We’re entering an exciting era of radio astronomy,” highlighted UCT researcher Dr Jacinta Delhaize. “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.”