La emisión infrarroja de galaxias activas
Nowadays it is accepted that all galaxies with significant bulge component contain a supermassive black hole (SMBH) in their centres. This SMBH plays an important role in the formation of galaxies, being quiet in some galaxies and accreting material and growing in others. The latter phenomenon is referred to as an active galactic nuclei (AGN) and it is very energetic, with the central region being able to reach luminosities as high as a few thousands that of the host galaxy. All AGN have the same components according to the simplest version of the unified model and emit in all the electromagnetic spectrum, with each AGN component peaking at a different range. The observational differences observed between different types of AGN are explained by orientation effects, with the obscuring dusty torus being the key ingredient to explain this orientation dependence. Since the torus reprocesses the optical/UV radiation from the accretion disk and re-emits in the IR range, it is important to study this IR emission to understand the dusty torus of the AGN.
The main goal of this thesis is to study the IR emission of AGN in nearby galaxies as well as active galaxies in cosmological fields. This thesis is divided into two different parts. The main objective of the first part is to select AGN in cosmological fields by their IR variability using Spitzer/MIPS 24 μm data while the objective of the second part is to study the dust heated by the AGN in nearby Seyfert galaxies using data from Herschel and from ground-based telescopes.