For a long time, astrophysics was dominated by the belief that giant jets of radio emission, radio outbursts blasting from central regions, were the exclusive privilege of elliptical galaxies. It was thought that only their calm, featureless internal environment could allow such colossal fountains of energy, powered by supermassive black holes, to form. However, a new study, based on archival images from the Hubble Space Telescope and radio sky surveys, has turned this notion on its head: bright radio fountains have also been found among spiral galaxies. The scientists deliberately selected 15 such objects for detailed study.

To visualize the geometry, imagine a spinning plate with a fountain in its center. The water jets shoot straight up and down, perpendicular to the plate's plane. Though simplified, this analogy captures the essence: radio outbursts in spiral galaxies erupt near the rotation axis, at a slight angle to the poles, piercing the interstellar medium. Most such galaxies are observed nearly edge-on, and their jets end in characteristic bright "hot spots"—regions where the particle stream collides with surrounding gas. Spectroscopic analysis of light (splitting the nuclear emission into individual wavelengths) revealed a curious duality: in the central regions, both accretion, the infall of matter onto the black hole, and bursts of star formation, i.e., the birth of new stars, occur simultaneously.

The study also delivered a cautionary surprise: many initial candidates turned out to be false. In those cases, radio outbursts from distant, unrelated sources simply shone through the spiral galaxy's disk, creating the illusion of an internal fountain. Such systems, however, became valuable finds in their own right: they offer a rare opportunity to study the invisible magnetic fields threading galactic disks, using the background radio emission as a probe. This discovery continues the path blazed a century ago by the pioneer of radio astronomy, Karl Jansky, who first detected cosmic radio signals and thereby opened a new window onto the universe.