The IBISCO survey: I. Multiphase discs and winds in the Seyfert galaxy
  Markarian 509
  We present the analysis of the ALMA CO(2-1) emission line and the underlying
1.2 mm continuum of Mrk509 with spatial resolution of 270 pc. This local
Seyfert 1.5 galaxy, optically classified as a spheroid, is known to host a
ionised disc, a starburst ring, and ionised gas winds on both nuclear and
galactic scales. From CO(2-1) we estimate a molecular gas mass
$M_{H_2}=1.7\times 10^9\, \rm M_{\odot}$, located within a disc of size 5.2
kpc, with $M_{dyn}$=(2.0$\pm$1.1) $\times$ $10^{10}\, \rm M_{\odot}$ inclined
at $44\pm10$ deg. The molecular gas fraction within the disc is
$\mu_{gas}=5\%$. The gas kinematics in the nuclear region within r=700 pc
suggests the presence of a warped nuclear disc. Both the presence of a
molecular disc with ongoing star-formation in a starburst ring, and the
signatures of a minor merger, are in agreement with the scenario where galaxy
mergers produce gas destabilization, feeding both star-formation and AGN
activity. The spatially-resolved Toomre Q-parameter across the molecular disc
is in the range $Q_{gas}=0.5-10$, and shows that the disc is marginally
unstable across the starburst ring, and stable at nucleus and in a lopsided
ring-like structure located inside of the starburst ring. We find complex
molecular gas kinematics and significant kinematics perturbations at two
locations, one within 300 pc from the nucleus, and one 1.4 kpc away close to
the region with high $Q_{gas}$, that we interpret as molecular winds. The total
molecular outflow rate is in the range 6.4-17.0 $\rm M_\odot/yr$. The molecular
wind total kinetic energy is consistent with a multiphase momentum-conserving
wind driven by the AGN with $\dot{P}_{of}/\dot{P}_{rad}$ in the range 0.06-0.5.
The spatial overlap of the inner molecular wind with the ionised wind, and
their similar velocity suggest a cooling sequence within a multiphase AGN
driven wind.
