Black Hole Runs Out of Gas, Rapidly Dims its Galaxy

Artist's impression of an active galactic nucleus (AGN) going through a bright and dim cycle. The upper panels show the entire galaxy and the lower ones show the central AGN as it grows dimmer over time due to a diminishing flow of gas. Credit: Chiba Institute of Technology

It’s not often that astronomers can observe huge changes in a galaxy’s brightness over the course of a few years. Most galaxies change in brightness (and other characteristics) over millions or billions of years. So, when images of the 10-billion-light-year distant galaxy J0218-0036 showed that it dimmed down by a twentieth of its previous brightness in just 20 years, observers were surprised. What could cause it to do that? That’s not “normal” for AGN.

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