Active galaxies: some so much and others so little

About the lecture

Many galaxies in the universe, including our own Milky Way, contain supermassive black holes at their centres (from a few million to billions of times the mass of the Sun). But only in a small fraction of these galaxies, the so-called “active galaxies”, do a series of mechanisms switch on in their nuclei, which can become very violent. These active nuclei produce enormous amounts of energy that cannot be explained by star formation alone, but are related to the accretion of matter onto the supermassive black hole. In the most active galaxies, quasars, the nucleus can emit as much light as a thousand galaxies like ours. In the least active, the active nucleus can almost go unnoticed. In this talk we will review the mechanisms that can switch on and feed the black hole, and how they may explain why some galaxies are much more active than others.

Text of the official description published by IAA-CSIC on YouTube.