Determination of the physical properties of AGN outflows: a new approach to kinematical modeling

During the last decades many observational evidences and theoretical studies highlighted the role of the supermassive black holes (SMBHs) at the center of galaxies in regulating the large scale galaxy properties. In particular, it emerged their pivotal role in regulating the dynamical state of the bulge, as well as their tight connection to the bulge mass and luminosity. The mechanism through which SMBHs and the galaxies communicate is known as active galactic nuclei (AGN) feedback. Such mechanism is favored by the interaction between the energy released by the accreting Black Holes (BHs) and the gas in the host galaxies. As matter falls onto the SMBHs, large amounts of energy are released in the form of radiation, outflows, and jets, which clear their path, sweeping the ambient gas away and heating the interstellar medium (ISM). As a consequence, outflows and jets might prevent the formation of new stars and further accretion of material on the central source, thus limiting their powering engine and terminating the active nucleus. To comprehend the impact of outflows and jets onto their host galaxy, a proper determination of their physical properties, with particular attention to their energetic budget, is needed per each gas phase. Over the past twenty years many theoretical models and hydrodynamical simulations have been proposed and attempted to predict the interaction mechanisms between outflows and their hosts. Nevertheless, up to today there is still one main challenge that prevents to put stringent constraints on theoretical predictions. Indeed, despite the constant upgrades of observing facilities and the plethora of outflows detected in various gas phases, a comprehensive kinematical model to interpret the data is lacking. Such lack prevents to take into account both observational effects, such as the point spread function (PSF), and projection effects, which are crucial to unveil the intrinsic 3D geometry and kinematics of outflows. As a consequence, despite the increasing detections of outflows from the local Universe up to high redshift, and the launch of state-of-the-art integral field spectrographs (IFS), we still cannot assess the outflow launching mechanism and the differential energetic impact they have on their hosts while crossing galactic scales. Additionally, understanding the link between sub-relativistic ultra fast outflows (UFOs) – launched on nuclear scales – and multi-phase galaxy-wide outflows through morphological and kinematic analysis is crucial to uncover the pathways of the SMBH–galaxy co-evolution. A truly comprehensive investigation of these processes requires high spatial resolution, high sensitivity, and wide wavelength coverage – conditions achievable only in nearby galaxies through joint observations with multiple facilities. To start completing the puzzle, with this PhD thesis we aim at providing strong observational constraints on the physical mechanism driving outflows in AGN by determining the 3D outflow geometry and kinematics, thus shedding light on one of the main drivers of galaxy evolution. In particular, in Chapter 1 we start with a broad overview of the gas physical properties in active and star forming galaxies from the local Universe up to the cosmic dawn. In Chapter 2 we present our innovative multi-cloud kinematic model MOKA3D, tailored to infer the kinematical and morphological properties of outflows and galactic discs with an innovative approach based on integral field unit (IFU) observations. At variance with previous kinematic models, MOKA3D takes into account observational effects like beam smearing and PSF convolution, reproducing with high accuracy the observed gas emission line on a spaxel-by-spaxel basis. In this chapter we also present the first application of MOKA3D to a restricted sample of three local (D ≤ 25 Mpc) AGN, which thanks to their proximity represent the perfect laboratories to test the capabilities of our model and investigate outflow properties. In Chapter 3 we expand our sample and present crucial improvements of the MOKA3D model which, combined with the high spatial resolution and large field of view (FOV) of the multi unit spectroscopic explorer (MUSE) at the very large telescope (VLT) allowed us to resolve the intrinsic velocity profile of AGN-driven outflows. Here, we present for the first time observational evidences of the peculiar outflow acceleration on physical scales of ∼ 1 kiloparsec from the central engine, consistent with hydrodynamical simulations and theoretical models. Such discovery represents the first step towards a comprehensive understanding of the outflow launching physics in AGN, providing crucial insights on the energy exchange mechanism between outflows and the ISM. In Chapter 4 we present state-of-the-art IFU observations of a sample of local active galaxies observed with the James Webb Space Telescope (JWST) and show evidence of a tight link between the outflow features inferred via optical and Mid-IR tracers. We present the first application of innovative diagnostic diagrams tailored to infer the ionization source exploiting dust-insensitive MIR tracers and present the improvements with respect to optical diagnostics. Chapter 5 is devoted to provide a detailed view of the physical conditions of the ISM in galaxies at Cosmic Dawn, before the onset of the intense accretion of matter onto the central SMBH. In this Chapter we carry out a detailed spatially resolved analysis of the ionized gas and stellar population properties and present a detailed overview of the peculiar conditions of the Universe at high redshift and how they evolve into the currently standard active galaxy that we observe in the local Universe. Including early-epoch galaxies in our investigation is important in order to close the loop of this thesis – from local systems, where the impact of the AGN of the host can be studied in exquisite detail, to the primordial galaxies where such mechanisms were first established. Finally, Chapter 6 is dedicated to summarize the results of this thesis and outline possible future developments.