In some cases, the black hole will even spew jets of plasma, millions of light-years across intergalactic space. The plasma gas is so hot that it’s essentially a soup of electrons moving close to the speed of light. These plasma jets glow at radio frequencies, so they can be seen with a radio telescope and are, aptly, named radio galaxies. In a recent episode of the astronomy podcast The Cosmic Savannah, I likened their appearance to two glow sticks (the plasma jets) poking out of a ball of sticky tack (the galaxy). Astronomers hypothesise that the plasma jets keep expanding outwards as time passes, eventually growing so large that they become giant radio galaxies.
Millions of normally sized radio galaxies are known to science. But by 2020 only about 800 giant radio galaxies had been found, nearly 50 years since they had been initially discovered. They were considered rare. However, a new generation of radio telescopes, including South Africa’s MeerKAT, have turned this idea on its head: in the past five years about 11,000 giants have been discovered.
MeerKAT’s newest giant radio galaxy find is extraordinary. The plasma jets of this cosmic giant span 3.3 million light-years from end to end – over 32 times the size of the Milky Way. I’m one of the lead researchers who made the discovery. We’ve nicknamed it Inkathazo, meaning “trouble” in South Africa’s isiXhosa and isiZulu languages. That’s because it’s been a bit troublesome to understand the physics behind what’s going on with Inkathazo.
