Radio jets launched by supermassive black holes are one of the potential drivers of multi-phase outflows and can alter the properties of the interstellar medium (ISM) of galaxies on (sub-)kpc scales. In order to investigate the impact of radio jets on the cold gas reservoirs of AGN, I analyzed ALMA CO(2-1) and CO(3-2) observations of the Teacup galaxy. This is a radio-quiet type-2 quasar with a compact low-power radio jet that subtends a small angle from the molecular gas disc. Enhanced emission line widths perpendicular to the jet orientation have been reported for several nearby AGN for the ionized gas. For the molecular gas in the Teacup, not only do we find this enhancement in the velocity dispersion but also a higher brightness temperature ratio (T32/T21) perpendicular to the radio jet compared to the ratios found in the galaxy disc. Our results and the comparison with simulations suggest that the radio jet is compressing and accelerating the molecular gas, and driving a lateral outflow that shows enhanced velocity dispersion and higher gas excitation. These results provide further evidence that the coupling between the jet and the ISM is relevant to AGN feedback even in the case of radio-quiet galaxies.

In this work we presented CO(2−1) and adjacent continuum observations of seven nearby radio-quiet type-2 quasars (QSO2s) obtained with ALMA at ∼0.2″ resolution (370 pc at z ∼ 0.1). These QSO2s are luminous (L[OIII]>108.5 L⊙), and their host galaxies massive (M*~1011 M⊙). The CO morphologies are diverse, including disks and interacting systems. The ionized and molecular gas kinematics and millimeter continuum emission indicate that these CO morphologies are most likely produced by AGN feedback in the form of outflows, jets, and/or shocks. 

The CO kinematics of the QSO2s with CO(2−1) revealed molecular outflows that are mostly coplanar with the CO disks. These outflows have maximum velocities of 200-350 km/s and outflow mass rates of 8-16 M⊙/yr,  lower than those expected from their AGN luminosities (Fiore+2017). 

This suggests that it is not only AGN luminosity that drives massive molecular outflows. Other factors such as jet power, coupling between winds, jets, and/or ionized outflows and the CO disks, and amount or geometry of dense gas in the nuclear regions might also be relevant. Thus, although we did not find evidence for a significant impact of quasar feedback on the total molecular gas reservoirs and star formation rates, it appears to be modifying the distribution of cold molecular gas in the central kiloparsec of the galaxies.

In my first postdoctoral position in Athens, Greece, in 2019 I joined the group of Prof. Kalliopi Dasyra as the scientific PI of the project entitled “Do massive winds induced by black-hole jets alter galaxy evolution? Evidence from galaxies in the ALMA Radio-source Catalog- ARC”. The goal was to study the importance of radio jets in shaping galaxy evolution and was the first attempt to build the CO luminosity functions of radio galaxies (RGs) using a representative sample of 120 RGs from the local Universe up to z ∼ 2.5 observed with ALMA  (66 ALMA +54 literature). This work demonstrates the potential of exploring the wealth of the ALMA archival observations, including calibrators, for scientific purposes. The local mass function reveals that the number density of low-z RGs with detectable molecular gas reservoirs is only a little lower (a factor of ∼4) than that of AGN in simulations. At 1 < z < 2.5, there is a significant decrease in the number density of RGs due to the rarity of bright RGs. The CO luminosity function of RGs derived in this work is useful for benchmarking cosmological simulations and constraining the gaseous content of RGs at the local Universe up to the star formation/activity history peak at z≲2.5, where feedback appears to be crucial for galaxy evolution.

In the Seyfert/nuclear starburst galaxy NGC 613, we have combined ALMA Cycles 3 and 4 observations at a spatial resolution of 17 pc. The morphology of CO(3-2) line emission reveals a 2-arm trailing nuclear spiral at r <100 pc inside the Inner Lindblad Resonance (ILR) ring. This nuclear spiral is efficiently driving gas towards the center in ∼10 Myr dynamical timescales. 

We find broad wings in the nuclear spectra of CO and dense gas tracers, with velocities reaching up to ±300 km/s, associated with a molecular outflow emanating from the nucleus (r ∼25 pc). We derive a molecular mass outflow rate of Mout =27 M⊙/yr.  The outflow is mainly boosted by the AGN through entrainment by the radio jet, but given the weak nuclear activity of NGC 613, we proposed that we might be witnessing a fossil outflow, resulted from a strong past AGN that now has already faded.

Left: the nuclear CO(3-2) spectrum  with the blue (-400 to -120 km/s) and red (120 to 300 km/s) wings associated to the outflow. Middle and right: the velocity distribution of the CO(3-2) emission with the VLA radio contours at 4.86 GHz and a zoom of the velocity distribution and the contours of the blue and red wings emission.

The “hot spot” HII/Sy galaxy NGC 1808 was studied using ALMA Cycle 3 observations at 12 pc spatial resolution. Inside the star-forming ring, a 2-arm spiral structure is clearly detected at ∼50 pc radius. We found that the nuclear spiral is kinematically decoupled from the larger disk, the position angle being tilted from 323◦ to close to 270◦ What is remarkable in our observations, is that the nuclear trailing spiral is even more contrasted in the dense gas tracers.  The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100 pc is feeding the nucleus on a timescale of five rotations or on an average timescale of ∼60 Myr. 

 We found a HCN enhancement in circumnuclear molecular gas around AGN, by measuring the HCN(4-3)/HCO+(4-3) and HCN(4-3)/CS(7-6) intensity ratios in the submillimetre diagram (Izumi et al. 2016). We find that the nuclear region of NGC 1808 presents line ratios that indicate excitation conditions typical of X-ray dominated regions in the vicinity of AGN.

There is a molecular outflow detected at ≥250 pc in the NE direction that is likely due to supernovae feedback and it is connected to the kpc-scale superwind. 

Our aim was to explore the close environment of AGN, and the dynamical structures leading to their fueling, through the morphology and kinematics of the gas inside the sphere of influence of the black hole.  We used ALMA observations of CO(3-2) emission in the NUGA sample of seven Seyfert/LINER galaxies at the unprecedented spatial resolution of 0.″1 = 4-8 pc. 

The observed maps reveal the existence molecular tori:   circumnuclear disk structures, defined by their morphology and decoupled kinematics. They have varying orientations along the line of sight, unaligned with the host galaxy orientation. The radius of the tori ranges from 6 to 27 pc and usually the torus and the AGN are slightly off-centered with respect to the bar-resonant ring position, implying that the black hole is wandering by a few 10 pc amplitude around the center of mass of the galaxy. 

During my B.Sc. and M.Sc. studies, I analyzed Spitzer/IRS spectra (5-35𝜇m) of ~100 Seyfert galaxies, a common type of AGN in the nearby Universe. I compared these spectra with theoretical spectral energy distribution (SED) from the CLUMPY torus models. The main goal was to discern the differences in the physical parameters of tori between type 1 and type 2 AGN. I found that the classification of a galaxy may also depend on the intrinsic properties of the torus clouds rather than simply on their inclination, in contradiction to the unification model orientation assumption, in agreement with previous studies using smaller samples.