'Echo Mapping' in Faraway Galaxies Could Measure Vast Cosmic Distances

A disk of hot material around a supermassive black hole emits a burst of visible light, which travels out to a ring of dust that subsequently emits infrared light

Matter swirling around supermassive black holes creates bursts of light that “echo” in nearby dust clouds. These traveling signals could serve as a new cosmic yardstick.

'Echo Mapping' in Faraway Galaxies Could Measure Vast Cosmic Distances