How Supermassive Black Holes Kill Off Old Galaxies


Image: Cheung et al
Image: Cheung et al
Galaxies get old and die. This is natural. Existing stars within an aging galaxy will eventually become dim and cool, while the galaxy itself—and the other galaxies it’s likely to merge with over time—will become diffuse and disordered. The dying galaxy will stop producing new stars in a process known as „quenching.“

By Michael Byrne | MOTHERBOARD

Galaxy quenching is a fairly mysterious subject. It happens when a particular galaxy has its supplies of cold gases shut off. No more cold gas, no more star formation. What’s weird is that galaxies appear to quench much earlier than should be expected given their gas supplies, which means that they don’t just run out. Something interferes instead—either the galaxy’s cold gas reserves are blocked (a process known as „strangulation“), or those supplies are ejected from the galaxy by some awesome force.

This awesome force has been theorized to be the presence of a supermassive black hole, and computer simulations have supported this idea. Now, as described in a paper published Wednesday in Nature, astrophysicists led by the University of Tokyo’s Edmond Cheung have used real-world spectroscopic observations to map the motions of ionized gas across a distant near-dormant galaxy nicknamed Akira.

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