The fueling of SMBH at the center of galaxies and the subsequent feedback from its active nuclei, are among the key processes to understand the concerted growth of galaxies and BH. AGN feedback is invoked to explain the formation of massive galaxies when we compare the luminosity function of galaxies to theoretical simulations based on the cold dark matter models (Silk and Mamon, 2012). Winds and outflows produced by the AGN can eject or heat the gas, terminate the star formation and through the lack of fuel for accretion, quench the black hole activity. Recent discovery of many massive molecular outflows (e.g., Feruglio et al., 2010; Fischer et al., 2010; Alatalo et al., 2011; Sturm et al., 2011; Dasyra and Combes, 2012; Veilleux et al., 2013; Cicone et al., 2014; Dasyra et al., 2014; García-Burillo et al., 2014) have been promoting the idea that winds may be major actors in sweeping the gas out of galaxies, in agreement with theoretical predictions of AGN driven winds models (Faucher-Giguère and Quataert, 2012; Zubovas and King, 2012, 2014). However, it is still difficult to distinguish the origin of the outflows, whether they are AGN-driven or starburst-driven.

On the other hand, AGN are fueled by accretion of material onto the BH and the gas component can form stars on its way to the BH (García-Burillo and Combes, 2012; Combes et al., 2014). It is important to study the efficiency of angular momentum transport in galaxy disks in order to understand how the star formation and nuclear activity are fueled and what are the timescales involved, since both feeding process rely on a common cold gas supply, but in very different periods of time (~10⁵ year for BH growth and ~10⁷⁻⁹ year for star formation; García-Burillo, 2016). In addition to this scenario, one of the outstanding problems is to identify the mechanism that drives gas from the disk toward the nucleus, removing its large angular momentum and forming large non-axisymmetric perturbations, such as bars or spirals.

This work aims to better understand the galaxies chemical and thermal evolution by studying in detail the physical processes acting on the nucleus of a sample of nearby AGN. Probing AGN feeding and feedback phenomena through the kinematic and morphology of the gas inside the central kpc have recently been possible due to the unprecedented Atacama Millimeter/Submillimeter Array (ALMA) spatial resolution (≲0.5″) and sensitivity. Since there are only a few AGN observed with high spatial resolution, we investigate the nuclear molecular emission in a sample of nearby AGN making use of spectroscopic techniques.

By applying the velocity channel maps on the dense molecular gas tracers, e.g., HCN, HCO⁺, CS, and mid transition of CO, we can access the gas kinematics. To detect possible inflows or outflows, we can compare the CO rotation curve with a rotational velocity model based on the Hα kinematics and then subtract the model to analyse the velocity residuals in order to search for blue and redshifted patterns. Another possibility is to explore the current models for the rotation curve, when previous Hα or H i are not available in the literature. One of this model is described by Bertola et al. (1991), assuming the gas is on circular orbits in a plane, υc=Ar/(r2+c2)p/2, where for p = 1 the velocity curve is asymptotically flat and p = 3/2 the system has a finite total mass, therefore we expect 1 ≤ p ≤ 3/2. The observed radial velocity at a position (R, Ψ) on the plane of the sky can be described as:

where θ is the inclination of the disk (with θ = 0 for a face-on disk), Ψ₀ is the position angle of the line of nodes, v_sys is the systemic velocity and R is the radius and A, c, and p are parameters of the model. In the cases of NGC 7213 and NGC 1808, we have used the Bertola et al. (1991) model to search for non-circular motions in their observed velocity field.

We are going to apply the same methodology to search for outflows and inflows in a modest sample of nearby Seyfert/LINERs galaxies that are part of a new ALMA follow-up of the—NUclei of GAlaxies (NuGa) project, a previous CO survey of low luminosity AGN performed with the IRAM PdBI. The new ALMA observations have the remarkable spatial resolution of ~0.06–0.09″.

AA has written the article; AA and FC have contributed to reduce the data; FC and SG-B have written the proposal; and all four authors have contributed to interpret the data and comment the paper.