Feeding and feedback in nuclei of galaxies

Our aim is to explore the close environment of Active Galactic Nuclei (AGN) and its connection to the host galaxy through the morphology and dynamics of the cold gas inside the central kpc in nearby AGN. We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of AGN feeding and feedback caught in action in NGC613 and NGC1808 at high resolution (few pc), part of the NUclei of GAlaxies (NUGA) project. We detected trailing spirals inside the central 100pc, efficiently driving the molecular gas into the SMBH, and molecular outflows driven by the AGN. We present preliminary results of the impact of massive winds induced by radio jets on galaxy evolution, based on observations of radio galaxies from the ALMA Radio-source Catalogue.Comment: 5 pages, 3 figures, to be published in Proceeding IAU Symposium No. 359, 2020, "Galaxy evolution and feedback across different environments", Eds. T. Storchi-Bergmann, R. Overzier, W. Forman and R. Riffe

Probing the active galactic nucleus unified model torus properties in Seyfert galaxies

We studied the physical parameters of a sample comprising of all Spitzer/Infrared Spectrograph public spectra of Seyfert galaxies in the mid-infrared (5.2–38 μm range) under the active galactic nucleus (AGN) unified model. We compare the observed spectra with ∼106 CLUMPY model spectral energy distributions, which consider a torus composed of dusty clouds. We find a slight difference in the distribution of line-of-sight inclination angle, i, requiring larger angles for Seyfert 2 (Sy 2) and a broader distribution for Seyfert 1 (Sy 1). We found small differences in the torus angular width, σ, indicating that Sy 1may host a slightly narrower torus than Sy 2. The torus thickness, together with the bolometric luminosities derived, suggests a very compact torus up to ∼6 pc from the central AGN. The number of clouds along the equatorial plane, N, as well the index of the radial profile, q, is nearly the same for both types. These results imply that the torus cloud distribution is nearly the same for type 1 and type 2 objects. The torus mass is almost the same for both types of activity, with values in the range of Mtor ∼ 104−107M . The main difference appears to be related to the clouds’ intrinsic properties: type 2 sources present higher optical depths τ V. The results presented here reinforce the suggestion that the classification of a galaxy may also depend on the intrinsic properties of the torus clouds rather than simply on their inclination. This is in contradiction with the simple geometric idea of the unification model

A plausible link between dynamically unsettled molecular gas and the radio jet in NGC 6328

We report the detection of outflowing molecular gas at the center of the nearby radio galaxy NGC6328 (z=0.014), which has a gigahertz-peaked spectrum radio core and a compact (2 pc) young double radio lobe tracing jet. Utilizing Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) and CO(3-2) observations, as well as a novel code developed to fit the 3D gas distribution and kinematics, to study the molecular gas kinematics, we find that the bulk of the gas is situated within a highly warped disk structure, most likely the result of a past merger event. Our analysis further uncovers, within the inner regions of the gas distribution (R<300 pc) and at a position angle aligning with that of the radio jet (150 degrees), the existence of two anti-diametric molecular gas structures kinematically detached from the main disk. These structures most likely trace a jet-induced cold gas outflow with a total lower limit mass of $2\times 10^6\,\mathrm{M_\odot}$ mass, corresponding to an outflow rate of $2\,\mathrm{M_\odot\,yr^{-1}}$ and a kinetic power of $2.7\times 10^{40}\,\mathrm{erg\,s^{-1}}$. The energy required to maintain such a molecular outflow is aligned with the mechanical power of the jet.Comment: 19 pages, 13 figures, Accepted for publication in A

ALMA reveals a compact and massive molecular outflow driven by the young AGN in a nearby ULIRG

The ultra luminous infrared galaxy (ULIRG) F13451+1232 is an excellent example of a galaxy merger in the early stages of active galactic nucleus (AGN) activity, a phase in which AGN-driven outflows are expected to be particularly important. However, previous observations have determined that the mass outflow rates of the warm ionised and neutral gas phases in F13451+1232 are relatively modest, and there has been no robust detection of molecular outflows. Using high spatial resolution ALMA CO(1-0) observations, we detect a kiloparsec-scale circumnuclear disk, as well as extended ($r\sim440$ pc), intermediate-velocity (300<|$v$|<400 km s$^{-1}$) cold molecular gas emission that cannot be explained by rotational disk motions. If interpreted as AGN-driven outflows, the mass outflow rates associated with this intermediate-velocity gas are relatively modest ($\dot{M}_\mathrm{out}=22$-$27$ M$_\odot$ yr$^{-1}$); however, we also detect a compact ($r_\mathrm{out}$<120 pc), high velocity (400<$v$<680 km s$^{-1}$) cold molecular outflow near the primary nucleus of F13451+1232, which carries an order of magnitude more mass ($\dot{M}_\mathrm{out}\sim230$ M$_\odot$ yr$^{-1}$) than (and several times the kinetic power of) the previously-detected warmer phases. Moreover, the similar spatial scales of this compact outflow and the radio structure indicate that it is likely accelerated by the small-scale ($r\sim130$ pc) AGN jet in the primary nucleus of F13451+1232. Considering the compactness of the nuclear outflow and intermediate-velocity non-rotating gas that we detect, we argue that high spatial-resolution observations are necessary to properly quantify the properties of AGN-driven outflows and their impacts on host galaxies.Comment: 11 pages, 7 figures, 1 table; accepted for publication in MNRA

Observational constraints on the stellar recycled gas in active galactic nuclei feeding

Near-infrared long-slit spectroscopy has been used to study the stellar population (SP) of the low luminosity active galactic nuclei (AGNs) and matched analogues (LLAMA) sample. To perform the SP fits we have employed the X-shooter simple stellar population models together with the STARLIGHT code. Our main conclusions are: The star formation history of the AGNs is very complex, presenting many episodes of star formation during their lifetimes. In general, AGN hosts have higher fractions of intermediate-age SP (light-weighted mean ages, L ≲ 4.5 Gyr) when compared with their analogues ( L ≲ 8.0 Gyr). AGNs are more affected by reddening and require significant fractions of featureless continuum and hot dust components. The ratio between the AGN radiated energy and the gravitational potential energy of the molecular gas (ERad/EPG) for the AGN is compared with the L and a possible anticorrelation is observed. This suggests that the AGN is affecting the star formation in these galaxies, in the sense that more energetic AGN [log(ERad/EPG) ≳ 3] tend to host nuclear younger SP ( L ≲4 Gyr). We found that the recent (t <2 Gyr) returned (recycled) stellar mass is higher in AGN than in the controls. We also provide evidence that the mass-loss of stars would be enough to feed the AGN, thus providing observational constraints for models that predict that AGN feeding is partially due to the recycled gas from dying stars

Une analyse multi-longueur d'onde des noyaux actifs proches : étude de l'alimentation et rétroaction des NAG

The fuelling of super-massive black holes at the centre of galaxies and the subsequent feedback when the nucleus has become active, are among the key processes to understand the concerted growth of galaxies and black holes. The goal of this PhD work is to probe AGN feeding and feedback phenomena through the kinematic and morphology of the gas inside the central kpc, which have recently been possible due to the unprecedented ALMA spatial resolution (~0.1’’) and sensitivity. The discovery of many massive molecular outflows in the last few years has given support to constrain AGN feedback mechanisms. However, it is still difficult to distinguish the origin of the outflows, whether they are AGN-driven or starburst-driven. Since there are only a few AGN observed with high spatial resolution, we propose to select a large range of nearby AGN (Seyferts, LINERs, radio galaxies) and perform a multi-wavelength analysis of the molecular and/or atomic gas footprints.L'alimentation des trous noirs super-massifs au centre des galaxies et la rétroaction ultérieure lorsque le noyau est devenu actif, sont parmi les processus clés pour comprendre la croissance concertée des galaxies et des trous noirs. L'objectif de ce travail de thèse est l’étude du phénomène de l’alimentation et de la rétroaction des Noyaux Actifs de Galaxies (NAG) à travers la cinématique et la morphologie du gaz à l'intérieur du kpc central, qui ont récemment été possibles grâce à la résolution spatiale et la sensibilité sans précédent du télescope ALMA (~0.1’’). La découverte de nombreuses éjections moléculaires massives au cours des dernières années a contribué à restreindre les mécanismes de rétroaction NAG. Cependant, il est toujours difficile de distinguer l'origine de ces éjections, soit par les NAG ou par les starbursts. Comme il n'y a que quelques NAG observés avec une haute résolution spatiale, nous proposons de sélectionner une large gamme des NAG proches (Seyferts, LINERs, galaxies radio) et effectuer une analyse multi-longueur d'onde sur les empreintes du gaz moléculaire et/ou atomique