“Echo Mapping” Light Bursts From Supermassive Black Holes in Faraway Galaxies to Measure Vast Cosmic Distances – SciTechDaily

Black hole accretion disk and torus. Credit: NASA/JPL-Caltech
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.
When you look up at the night sky, how do you know whether the specks of light that you see are bright and far away, or relatively faint and close by? One way to find out is to compare how much light the object actually emits with how bright it appears. The differen…

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