Plasma conditions in different emitting regions of active galactic nuclei

Abstract

Active Galactic Nuclei (AGNs) are powerful energy sources in the Universe, emitting radiation from the gamma to radio spectral range. Different physical processes are present in the emitting plasma around the super-massive black hole, that is supposed to be in the center of an AGN. Here we present an overview of plasma conditions in emitting regions of AGNs. We start from the X-ray emitting region, which is close to the super-massive black hole, discussing the physics and geometry of the region. In more details we discuss the plasma that emits broad emission lines, i.e. the Broad Line Region, and at the end we present methods to determine the plasma conditions in the Narrow Line Emitting Region using forbidden, collisionally excited, emission lines.