In the centers of galaxy groups and clusters, the hot diffuse gas is dense enough that it ought to cool on timescales of tens to hundreds of millions of years, funneling cool gas toward the center of the cluster. This phenomenon, known as a “cooling flow”, should lead to massive starbursts at the centers of clusters, which we generally do not observe. It is now understood that energetic jets launched from the supermassive black hole at the center of each cluster are likely responsible for heating the surrounding medium and preventing cooling flows from forming (see picture to the right). These jets appear to be acting as a thermostat for the hot gas on large scales, moderating cooling with incredible precision.
There are many open questions remaining in how active galactic nuclei (AGN) moderate cooling in clusters. Our group is working on addressing many of these questions, including:
Below are some relevant papers and links to ongoing collaborations/efforts.