A radio telescope, like a sensitive ear, picks up the whispers of distant galaxies. Hidden among that noise are giants — giant radio sources. These are clouds of charged particles ejected from the vicinity of supermassive black holes. They stretch across millions of light-years — tens of times the size of our own galaxy.

Astronomers combed through the TGSS ADR1 sky survey and found 5595 such objects. Of these, 4566 are new — no one had seen them before. The search was automated: a neural network spotted blobs on the radio maps, and then a likelihood method picked out the largest ones. The biggest candidate spans 4.5 megaparsecs: that's like lining up 150 of our galaxies end to end.

The researchers measured how bent these giants are. It turns out most are nearly straight — the median bending angle is only 11 degrees. But there are exceptions: rare powerful sources larger than a megaparsec don't fit simple growth models. It seems they are inflated not only by the black hole's jet but also by the pressure of the surrounding gas.

286 candidates live inside galaxy clusters. There, the intergalactic gas is denser, and it can compress or, conversely, puff up these clouds. Now astronomers can test how the environment affects the growth of these giants.