Abstract

SUPERMASSIVE BLACK HOLE FEEDING

Supermassive black holes (SMBHs) form predominantly by accreting gas from an accretion disc, which is efficient only at radii < 0.001 pc. As this is well inside the region where the SMB Hs gravity dominates, it remains unclear how material to be accreted can lose its angular momentum to reach these scales. Here, I will detail a possible solution to this problem, which is based on the cancellation of angular momenta of different inflows onto the innermost neighbourhood of the SMBH .

CAPTURE OF INTERSTELLAR ASTEROIDS AND COMETS

The recent by fly-bys of ‘Oumuamua and Borisov suggest a large space density of such interstellar asteroids and comets. I investigate the possibility of capturing such objects into the Solar system via a fly-by of Jupiter or Saturn, presenting analytical arguments and estimates as well as results of various numerical simulations. The most likely captures occur for an incoming speed of around 0.6 km/s and populate orbits akin to those occupied by long-period comets. We estimate that the Solar system may contain around 10000 captured Oumuamua-like asteroids and 100 captured comets