The IBISCO survey: I. Multiphase discs and winds in the Seyfert galaxy Markarian 509

TL;DR

This study analyzes ALMA observations of Mrk509, revealing a complex, multiphase molecular gas environment with winds and signs of galaxy interactions, shedding light on AGN feeding and feedback mechanisms.

Contribution

First detailed ALMA CO(2-1) analysis of Mrk509 showing multiphase gas, winds, and merger signatures, advancing understanding of AGN-host galaxy interactions.

Findings

Molecular gas mass estimated at 1.7×10^9 M_sun within a 5.2 kpc disc.

Detection of molecular winds with outflow rates 6.4-17.0 M_sun/yr.

Evidence of a warped nuclear disc and signs of galaxy merger influence.

Abstract

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.