Quenching (astronomy)

Quenching mechanisms

Active supermassive black holes

Evidence suggests that active supermassive black holes may drive quenching. The strong jets of some active supermassive black holes may heat up cold gas, thus suppressing star formation.

Environmental quenching

Several proposed galaxy quenching mechanisms rely on the environment a galaxy is situated in. One example of this is when a galaxy passes through a dense intracluster or intergalactic medium. The motion of the galaxy through this medium creates a ram pressure force which can strip gas away from the galaxy. Through this mechanism, known as ram pressure stripping, galaxies can be depleted of gas.

Galaxy Mergers

Inflows of gas from galaxy mergers can activate supermassive black holes within galaxies, thereby resulting in quenching via feedback from active galactic nuclei jets. Merger events can also trigger rapid bursts of star formation. This rapid star formation can lead to high rates of events like supernovae, which disrupt cold gas. This quenched state is sometimes called a post-starburst galaxy.

Morphological quenching

In morphological quenching, a galaxy’s evolution from a disk to a spheroid can reduce the efficiency of star formation over time, leading to lowered rates of star formation.

Reionization

In the Epoch of Reionization, the first generation of stars heated gas throughout the universe. This process is thought to have quenched some smaller dwarf galaxies with small cold gas reservoirs.