| Abstract [eng] |
Some 6 Myr ago there was a period of increased nuclear activity in the Milky Way and it could be responsible for the formation of the Fermi bubbles. In this work we assess if a similar period of activity could be initiated by a collision between an infalling gas cloud and a gas ring currently found in the Galactic centre. We investigate how the accretion rate and the morphology of the resultant system depend on the initial collision angle. We also assess whether there is significant star formation in the central parsec. The main objective of this work is to: find out if a collision between a CNR-like ring and a molecular cloud explain the AGN episode that happeded ~6 Myr ago and the structures observed in the GC today. The main tasks of this work are to: Determine the morphology of the system following the collision and compare it to the observed structures in the Galactic centre. Determine how much mass was accreted by the central black hole and estimate the energy released during the activity period. Determine the star formation rate following the collision and investigate it's spatial distribution. After analysing the data, these conclusions were drawn: The morphology of the resultant system varies dependant on the initial collision angle; large angles result in twice as compact systems as the initial ring with larger mass fraction concentrated in warped central structures. Up to half of the initial system gas mass is fed to the central SMBH following the steepest angle collisions; mass infall is sufficient to generate energy required for \textit{Fermi} bubble formation, but significant portion of mass is lost due to accretion being too rapid; a gas outflow from the accretion disc could extend the activity period. Low angle collisions produced significant star formation in the outer rings, while large angle collision resulted in a more rapid star formation in the central discs; the highest average rate of star formation was found in models with collision angles 150 deg <= gamma < 170 deg; the average fragmentation rate in these examples is ~0.28 Ms/yr. |
