Black holes may shut down stellar factories

Galaxies stop forming stars despite access to raw materials

4:19pm, March 5, 2014

DEAD GALAXY  The giant elliptical galaxy NGC 5044, seen in this composite image, is filled with cold gas, yet it is not making stars. New research suggests a black hole may be to blame. The galaxy is filled with threads of warm hydrogen gas (red) that snake through an atmosphere of hot gas (blue). Stars appear white.  

Supermassive black holes might slowly suffocate galaxies. The suggestion runs counter to astronomers’ notion that galaxies stop forming stars when they run out of cold gas. But researchers have found a cache of galaxies loaded with cold gas that aren’t making stars. The team’s observations suggest that the galaxies’ central black holes stirred up the gas and shut down the stellar assembly lines.

Over the last decade, astronomers have learned that black holes can drive the fates of entire galaxies. “It’s a bit like an orange affecting the Earth,” says Andrew Fabian, an astronomer at the University of Cambridge. “These black holes are enormously powerful. They’re emerging as an important factor in the way galaxies operate.”

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