It was once believed that only elliptical galaxies could spawn giant streams of radio emission — radio jets emanating from central supermassive black holes. A new study proves otherwise: spiral galaxies also host powerful radio fountains. Researchers selected 15 such objects using Hubble images and radio sky data.

To picture the difference, imagine a spinning plate with a fountain at its center. Water jets shoot straight up and down, perpendicular to the plane. In the same way, radio jets in spiral galaxies burst out near the rotation axis, at a slight angle to the poles. We see most of these galaxies almost edge-on, and their jets end in bright 'hot spots'. Light analysis of the nuclei revealed that matter is simultaneously falling into the black hole and new stars are being born.

Unexpected twist: many candidates turned out to be false positives. Radio jets from distant sources simply shone right through a spiral galaxy, creating an illusion. Such systems offer a rare chance to study invisible magnetic fields inside galactic disks. This discovery builds on the work of Karl Jansky, who first detected a cosmic radio signal a century ago.