Dynamical model of an obscuring clumpy torus in AGNs: I. Velocity and
  velocity dispersion maps for interpretation of ALMA observations
  We have developed the dynamical model of a clumpy torus in an active galactic
nucleus (AGN) and compared to recent ALMA observations. We present $N$-body
simulations of a torus in the field of a supermassive black hole (SMBH), made
of up to $N=10^5$ gravitationally interacting clouds. As initial conditions, we
choose random distributions of the orbital elements of the clouds with a
cut-off in the inclination to mimic the presence of wind cones produced at the
early AGN stage. When the torus reaches an equilibrium, it has a doughnut
shape. We discuss the presence of box orbits. We have then constructed the
velocity and velocity dispersion maps using the resulting distributions of the
clouds at equilibrium. The effects of torus inclination and cloud sizes are
duly analyzed. We discuss the obscuration effects of the clouds using a ray
tracing simulation matching the model maps to ALMA resolution. By comparing the
model with the observational maps of NGC 1068 we find that the SMBH mass is
$M_\text{smbh}=5\times 10^6 M_\odot$ for the range of the torus inclination
angles $45^\circ - 60^\circ$. We also construct the velocity dispersion maps
for NGC 1326 and NGC 1672. They show that the peaks in the ALMA dispersion maps
are related to the emission of the torus throat. Finally, we obtain the
temperature distribution maps with parameters that correspond to our model
velocity maps for NGC 1068. They show stratification in temperature
distribution with the shape of the high temperature region as in the VLTI/MIDI
map.
