Identification of active galactic nuclei through different selection techniques

Abstract

The most recent studies suggest that almost all galaxies in the Local Universe host Super-Massive Black Holes (SMBHs) in their center. SMBHs are responsible for the most powerful phenomena in the Universe, the Active Galactic Nuclei (AGN). When SMBHs accrete matter, strong radiation is emitted at all wavelengths of the electromagnetic field. The complete census of the various populations of AGN and the construction of samples with high statistical significance are essential to understand the evolution of the SMBHs and the host galaxies in the history of the Universe. The present doctoral thesis focused on comparing different AGN detection techniques. In particular, AGN selection techniques based on photometric and spectroscopic data were used from different wavelength regimes of the electromagnetic spectrum (optical, infrared, X-rays) as well as techniques that are based on flux variability. Comparing the methods with each other, the observational and physical AGN properties were studi ...