Evidence shows, that some
black holes have killed star formation in their galaxies has come to light in a study that peers back 12.5 billion years
Stars form when cold clouds
of molecular hydrogen gas collapse, fragment, and condense. This process of star formation continues in many other galaxies
But some, such as large
elliptical galaxies, appear to have ended their star formation billions of years ago.
feedback, in the form of
powerful radiation emitted by material swirling around a black hole can heat molecular gas in the galaxy and prevent it from collapsing to form stars.
Such galaxies are called
"red and dead," because once star formation shuts down, the only stars that remain are long-lived, cool red stars.
The red-and-dead galaxies
had stronger black hole activity than the galaxies that were still forming stars during the same period.