Unveiling the dust-obscured activity of the universe through cosmic time: the view from the ALMA A3COSMOS survey

The derivation of statistical quantities, such as the LF and the SFRD, has allowed us to track how the overall galaxy population has undergone a transformation across cosmic time, both in demography and in typical luminosity. A significant fraction of the SFRD has come from dust-obscured sources. Thanks to the capability of ALMA to perform deep blind surveys in the mm/sub-mm it has been possible to study the evolution of dust obscured galaxies fainter than the sub-mm galaxies up to z~6, but these studies are limited by the small FOV of ALMA. To overcome this limitation, the A3COSMOS has been developed with the goal of collecting the ALMA archival images in the COSMOS field to perform statistical studies. In this Thesis, we present the method developed to homogenize the A3COSMOS collection of pointings, use them for statistical studies and for deriving evolutionary properties. Indeed, we were able to obtain the IR-LF of SF-galaxies from the A3COSMOS,, in a wide redshift range (0.5 < z < 6), finding strong luminosity and density evolution with redshift. We therefore derived the dust-obscured SFRD, whose redshift evolution seems to suggest that a significant fraction of the star formation occurs in obscured galaxies even at 4<z<6. Comparing our result with models, we found that they struggle in reproducing the bright-end of the luminosity and SFRF, especially at z > 2. To further investigate the properties of the A3COSMOS database, we derived the dust mass function and density up to z ∼ 6, finding a smooth decreasing trend in the dust mass density from z ∼ 1 to z ∼ 6. In future works, we plan to investigate more deeply the connection between galaxies and SMBHs evolution, by deriving the BHARD and by tracing its evolution over the redshift range covered by the A3COSMOS sample.