Evolution of the galactic cores and structure of the molecular gas tori

Using two different kinds of state-of-the art numerical simulations, we discuss 1) formation of a spiral galaxy and its stellar/gaseous cores, and 2) multi-phase gas models in the circum nuclear region and their "pseudo-observations" using 3-D non-LTE radiation transfer calculations for molecular lines. We found that a galactic core in a spiral galaxy seen in our N-body/SPH simulations coevolves with the galaxy itself, as a result the average mass ratio is about 0.01. The spin-axis of the core is frequently changed associating with major-mergers, where the mass accretion rate for the central 0.5 kpc is also temporally enhanced. We expect that the "obscuring molecular tori" around AGNs is very inhomogeneous and turbulent on a pc-scale, and this could be resolved in the nearby active galaxies using the ALMA. We also found that the CO-to-H2 conversion factor (X-factor) calculated from 12CO (J = 1-0) is NOT uniformly distributed in the central 100 pc region, but X_{CO (J=3-2)} is more uniform, and ∼0.3×1020 cm-2 (K km s-1)-1 is suggested.