Literatura académica sobre el tema "NGC 6810"

The observed properties of galaxies and supermassive black holes (BH) at their centers suggest that there must be a non-gravitational feedback mechanism regulating their evolution. These are the discrepancy at low and high masses between the observed stellar mass function of galaxies and that predicted by ΛCDM models, the scaling relations between the mass of BHs and the velocity dispersion, mass and luminosity of the host galaxy spheroid and the similarity between BH growth and star formation cosmic histories. Models of galaxy formation and evolution in fact routinely include feedback from active galactic nuclei (AGN) and supernovae (SNe), which can successfully reproduce the observed properties cited above. Models consider the following two types of AGN feedback: the radiative mode (or quasar mode), that operates during a luminous AGN phase through winds powered by radiation pressure, and the kinetic (or radio) mode, in which kinetic energy is released by the AGN on longer timescales through relativistic jets, which heat the surrounding halo in galaxy clusters, thus preventing cooling and further accretion on the central galaxy, and consequently further star formation. So far, the clearest observational evidence of AGN feedback comes from the kinetic mode in massive central cluster galaxies. Radiative feedback is instead more elusive, and has been recently revealed in action only in a few luminous quasars around the peak of AGN activity history (z~2), where most powerful outflows are observed. However, it is not possible to study high-z quasar outflows on small spatial scales (<100 pc), being poorly-resolved or even unresolved in observations, due to their large distances. This can lead to systematics and uncertainties in the determination of outflow properties and forces to make some assumptions on them, which further increases the uncertainties on the outflow energetics and complicates the evaluation of the impact of outflows on host galaxies and the comparison with models. On the contrary, due to their vicinity, nearby active galaxies are ideal laboratories to explore in detail outflow properties, their formation and acceleration mechanisms, as well as the effects of AGN activity on host galaxies. This work focuses on investigating the properties of outflows in nearby Seyfert galaxies, the physical conditions of the ionized gas and the interplay between nuclear activity and star formation in the galaxy, thanks to the unprecedented combination of spatial and spectral coverage provided by the integral field spectrograph MUSE at the Very Large Telescope (VLT). We introduce our optically- and X-ray selected sample of nearby Seyferts, called MAGNUM survey. We present our MUSE emission-line flux and kinematic maps of the 10 objects we have analyzed so far, including a star-forming galaxy, NGC 6810, to study the properties of a starburst outflow for comparison as well. We map the ionized gas down to spatial scales as low as ~10 pc. We find ubiquitous ionization cones and outflows with various morphologies and extensions, from a few hundred pc to several kpc. We detect peculiar kinematic features suggestive of outflows with hollow-conical structures. We also identify enhanced linewidths perpendicular to radio jets, which point to a correlation between the presence of jets and perpendicular turbulent or outflowing gas motions. We then focus on a detailed multi-wavelength study of the ionized gas and outflow, in terms of physical properties, kinematics, and ionization mechanisms, in one specific galaxy of our sample, NGC 1365, from MUSE in optical band and Chandra satellite in X-rays. Here we map a kpc-scale biconical outflow ionized by the AGN prominent in [O III], while Hα emission traces star formation in a circumnuclear ring and along the bar of the galaxy. Soft X-rays are mostly due to thermal emission from the star-forming regions, but we manage to isolate the AGN photoionized component which matches the [O III] emission from MUSE. We map the mass outflow rate of the galactic ionized outflow, which matches that of the nuclear X-ray wind and then decreases with radius. The integrated mass outflow rate, kinetic energy rate, and outflow velocity are broadly consistent with the typical relations observed in more luminous AGN. We extend our analysis to the nearby star-forming galaxy NGC 6810, whose bipolar galactic ionized outflow we map with MUSE. We determine the dominant ionization mechanism in the outflow, its density and ionization parameter, discovering the first case of star formation occurring within an outflow in an unambiguously star-forming galaxy. We finally investigate with MUSE also the kinetic AGN feedback, by studying the ionized gas enshrouding the X-ray cavity inflated by radio jets around the massive radio-galaxy 3C 317 at the center of the local cluster Abell 2052. Thanks to MUSE capabilities, by mapping the warm gas filaments enshrouding the bubble we are able to directly measure the expansion velocity of the cavity, which usually is instead assumed or derived from indirect and model-dependent methods.

Supermassive black holes (SMBH) are now thought to exist at the center nearly all massive galaxies. Not only are they thought to be ubiquitous, but it was also discovered nearly two decades ago that the mass of these SMBHs correlate strongly with properties of their host galaxies including bulge stellar velocity dispersion (MBH-sigma) and bulge luminosity (MBH-Lbulge). This correlation was not expected due to the tiny size of the SMBH gravitational sphere of influence compared to the size of the host galaxy, and imply a connection between the two, but this connection is still not well-understood. One step toward understanding this connection is to accurately measure the masses of these black holes. Two of the most common direct SMBH mass measurement techniques are stellar dynamical modeling (SDM), which generally only applies to quiescent galaxies, and reverberation mapping (RM), which can only be applied to active galactic nuclei (AGN) that exhibit broadened emission lines. Due to the unknown geometry of the region that produces these broad lines, the whole RM sample of black hole masses generally needs to be multiplied by a constant called the f-factor to bring it into agreement with the SDM sample on the MBH-sigma relation. It is unknown how well this f-factor, being a population average, applies to individual RM masses. It would therefore be useful to measure an SMBH mass with both methods simultaneously to test whether they produce the same black hole mass. However, because the RM and SDM techniques usually apply to galaxies that are not possible for both, this has only been attempted twice before (NGC 3227 and NGC 4151). The purpose of this dissertation is to apply SDM to the SMBH at the center of NGC 6814 for which there already exists an RM mass. This makes it only the third broad-lined AGN for which an SDM mass has been derived. In order to perform SDM accurately, the distance to the galaxy needs to be well-constrained as the error in the SDM mass scales linearly with distance. Because no adequate distance measurements already exist, the first half of this dissertation is devoted to deriving a Cepheid distance to NGC 6814 from V- and I-band HST WFC3 time series photometry. We measure the distance to NGC 6814 to be 17.54 +1.44/-1.33 Mpc. In the second half, we incorporate that distance measurement into our stellar dynamical modeling on Gemini NIFS+Altair IFU data of NGC 6814's central 1.55''x1.55''. We derive a mass of 1.19 +37.57/-1.17 x108 solar masses, and best fit mass-to-light ratio of 0.948 +0.032/-0.208 in solar units. This mass is nearly an order of magnitude larger than the RM mass but has a 3-sigma range spanning nearly three orders of magnitude. We describe possible reasons for our larger-than-expected mass value, such as the existence of a bar, which would not be well-modeled by an axisymmetric dynamical code. Finally, we describe future steps that may be taken to better constrain the mass, such as creating more models to further explore parameter space.