Speaker
Description
Active Galactic Nuclei (AGN) are quite unique astronomical sources emitting over about 20 orders of magnitude in frequency, with different electromagnetic bands providing windows on different sub-structures and their physics. They come in a large number of flavours only partially related to intrinsic differences. I will highlight the types of sources selected by different bands, the relevant selection effects and biases, and the underlying physical processes, emphasizing the gamma-ray band. I will then look at the “big picture” by describing the most important parameters one needs to describe the variety of AGN classes. I will then conclude with a look at the most pressing open issues and the main new facilities, which will flood us with new data to tackle them.
