The Life Cycle of the Central Molecular Zone. II: Distribution of atomic
  and molecular gas tracers
  We use the hydrodynamical simulation of our inner Galaxy presented in
Armillotta et al. (2019) to study the gas distribution and kinematics within
the CMZ. We use a resolution high enough to capture the gas emitting in dense
molecular tracers such as NH3 and HCN, and simulate a time window of 50 Myr,
long enough to capture phases during which the CMZ experiences both quiescent
and intense star formation. We then post-process the simulated CMZ to calculate
its spatially-dependent chemical and thermal state, producing synthetic
emission data cubes and maps of both HI and the molecular gas tracers CO, NH3
and HCN. We show that, as viewed from Earth, gas in the CMZ is distributed
mainly in two parallel and elongated features extending from positive
longitudes and velocities to negative longitudes and velocities. The molecular
gas emission within these two streams is not uniform, and it is mostly
associated to the region where gas flowing towards the Galactic Center through
the dust lanes collides with gas orbiting within the ring. Our simulated data
cubes reproduce a number of features found in the observed CMZ. However, some
discrepancies emerge when we use our results to interpret the position of
individual molecular clouds. Finally, we show that, when the CMZ is near a
period of intense star formation, the ring is mostly fragmented as a
consequence of supernova feedback, and the bulk of the emission comes from
star-forming molecular clouds. This correlation between morphology and star
formation rate should be detectable in observations of extragalactic CMZs.
