GRAVITATIONAL INSTABILITIES IN GASEOUS DISCS AND THE FORMATION OF SUPERMASSIVE BLACK HOLE SEEDS AT HIGH REDSHIFTS

In this paper, I will review the the recent progresses in understanding the nonlinear evolution of gravitationally unstable gaseous discs. Gaseous accretion discs are a fundamental ingredient in the modeling on very diverse physical systems, spanning from the large scale discs that provide the fueling for supermassive black holes (SMBH) in the nuclei of active galaxies (AGN) to the smaller scale discs surrounding young stars, which are thought to be the site where planet formation occurs. Gravitational instabilities (GI) might play an important role in determining the structure and the evolution of such discs in many cases. The advances in numerical techniques have recently made possible to run complex simulations of the non-linear behaviour of such collective phenomena, leading to a deeper understanding of important related aspects, such as fragmentation and angular momentum transport. I will also present one specific example that shows the importance of gravitational instabilities in a system of considerable astrophysical relevance: high-redshift proto-galaxies, where GI might lead to the formation of the seeds of SMBHs.