| Abstract [eng] |
It is well established that nearly every massive galaxy hosts a super massive black hole (SMBH). Matter accretion onto this massive and compact object produces vast amounts of energy, creating an active galactic nucleus (AGN). Episodes of activity are common during galactic evolution, usually lasting for up to a Myr, with luminosities near the Eddington limit. The AGN produces vast amounts of ionizing radiation, heats surrounding matter and forms a relativistic particle wind. The wind interacts with the surrounding diffuse medium, forming galaxy-wide outflows. Our Galaxy is no exception, there is evidence of a recent activity episode in the form of the Fermi bubbles. Barred spiral galaxies commonly have substantial amounts of molecular gas in the central kpc. Gravitational potential of the bar mediates gas transport from the galactic disc to the vicinity of the SMBH and forms ring-like structures. In our Galaxy a ~200 pc twisted ring is observed known as the Central Molecular Zone (CMZ); similar structures are prevalent in other barred spiral galaxies. CMZ is known for high densities, elevated amounts of ionizing radiation and surprisingly low star formation rates. The effect of the galactic activity on this warm gas is largely unexplored, but such conditions could indicate a transient state - a CMZ recovering from an episode of galactic activity. Effects of AGN-driven outflows on star formation have been explored quite extensively, but conditions in the CMZ are peculiar, thus the effect of the outflow is largely unknown. In general, outflows can compress the gas and induce star formation, or expel the gas quenching it. They also can inhibit gas transport to the CMZ producing long-lasting effects. I use the hybrid SPH/N-body code ‘Gadget 3’ to model an episode of galactic activity and measure star formation rates and morphological changes of CMZ. Initial conditions resemble the central few kpc of our Galaxy. I model multiple systems, with AGN Eddington ratios of 0.0, 0.5, 1.0. I include hydrodynamics, gravitation, cooling, AGN feedback and star formation. I find increased star formation rates and more massive star clusters with AGN luminosity of 0.5 Eddington limit, compared to other luminosities. AGN of Eddington luminosity produces clusters with elliptical orbits, with periapses of tens of pc. Such clusters could be used as indicators of a recent episode of activity. The findings are consistent with observed young, massive clusters near Sgr A*, suggesting an episode of near-Eddington luminosity that lasted ~1 Myr; the CMZ is in a transient state recovering from such an episode that ended ~ 5 Myr ago. |
