Supermassive black holes could be quenching star formation in elliptical galaxies, forcing them to appear "red and dead," a new study reports.
Astronomers have long wondered why giant elliptical galaxies stop forming stars, becoming dominated over time with small, long-lived stars with a distinctive reddish tinge. Conventional wisdom had held that these galaxies lack the cold gas necessary for star birth.
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But new observations suggest that a rethink is in order. Some big ellipticals do indeed harbor large amounts of cold gas - but these reservoirs likely get heated up or driven off by powerful jets of material blasted out by supermassive black holes, which lurk at the heart of most if not all galaxies. [The Strangest Black Holes in Space]
"These galaxies are red, but with the giant black holes pumping in their hearts, they are definitely not dead," study lead author Norbert Werner, of Stanford University, said in a statement.
Werner and his colleagues studied eight giant elliptical galaxies using the European Space Agency's Herschel Space Observatory. They found that six of the eight have lots of cold gas, which Herschel detected as far-infrared emissions from carbon ions and oxygen atoms.