Where do blazars hide their neutrino factories?

High-energy neutrinos from blazars (jets from supermassive black holes) should be common but are rarely detected. By combining radio observations with emission models, researchers found that efficient neutrino production requires intense radiation fields—conditions met only in regions far from where the brightest electromagnetic radiation originates. This separation explains why blazar-neutrino detections are so rare and suggests future searches should target jets with unusual internal structures.