Academic literature on the topic 'NGC 5643'

We study the multiphase feedback processes in the central ∼3 kpc of the barred Seyfert 2 galaxy NGC 5643. We used observations of the cold molecular gas (ALMA CO(2−1) transition) and ionized gas (MUSE IFU optical emission lines). We studied different regions along the outflow zone, which extends out to ∼2.3 kpc in the same direction (east-west) as the radio jet, as well as nuclear and circumnuclear regions in the host galaxy disk. The CO(2−1) line profiles of regions in the outflow and spiral arms show two or more different velocity components: one associated with the host galaxy rotation, and the others with out- or inflowing material. In the outflow region, the [O III]λ5007 Å emission lines have two or more components: the narrow component traces rotation of the gas in the disk, and the others are related to the ionized outflow. The deprojected outflowing velocities of the cold molecular gas (median Vcentral ∼ 189 km s−1) are generally lower than those of the outflowing ionized gas, which reach deprojected velocities of up to 750 km s−1 close to the active galactic nucleus (AGN), and their spatial profiles follow those of the ionized phase. This suggests that the outflowing molecular gas in the galaxy disk is being entrained by the AGN wind. We derive molecular and ionized outflow masses of ∼5.2 × 107 M⊙ (αCOGalactic) and 8.5 × 104 M⊙ and molecular and ionized outflow mass rates of ∼51 M⊙ yr−1 (αCOGalactic) and 0.14 M⊙ yr−1, respectively. This means that the molecular phase dominates the outflow mass and outflow mass rate, while the kinetic power and momentum of the outflow are similar in both phases. However, the wind momentum loads (Ṗout/ṖAGN) for the molecular and ionized outflow phases are ∼27−5 (αCOGalactic and αCOULIRGs) and < 1, which suggests that the molecular phase is not momentum conserving, but the ionized phase most certainly is. The molecular gas content (Meast ∼ 1.5 × 107 M⊙; αCOGalactic) of the eastern spiral arm is approximately 50−70% of the content of the western one. We interpret this as destruction or clearing of the molecular gas produced by the AGN wind impacting in the eastern side of the host galaxy (negative feedback process). The increase in molecular phase momentum implies that part of the kinetic energy from the AGN wind is transmitted to the molecular outflow. This suggests that in Seyfert-like AGN such as NGC 5643, the radiative or quasar and the kinetic or radio AGN feedback modes coexist and may shape the host galaxies even at kiloparsec scales through both positive and (mild) negative feedback.

AbstractIn this work we derive stellar archaeology and kinematics of the central 400 pc of NGC 5643. The star formation history (SFH) reveals nuclear contribution of stellar populations older (20% older than 3.5 Gyr) and younger (60% younger than 320 Myr) as compared to the circumnuclear region. The [OIII] 5007 Å kinematics reveals the eastern ionization cone with an outflow (−60 km/s ⩽ v ⩽ 120 km/s).

Considering the current skepticism surrounding the impact and efficacy of nonprofit and nongovernmental organizations, some believe that a unique category of innovator known as the social entrepreneur may be society’s best hope for bringing innovative, scalable, and systemic solutions to bear on the world’s most intractable problems. Social entrepreneurs, as defined by Ashoka, have a unique set of characteristics that determine not only how they move within the world of social change-making but also how they communicate their ideas and mission to the public. This exploratory study reviewed how social entrepreneurs currently use documentary film and visual media in their communications strategy and public relations practice, what that tells us about the emerging culture of social entrepreneurs, and whether documentary, as defined by John Grierson, is an appropriate tool for these organizations. The author interviewed three founders, three communications professionals, and three filmmakers associated with social entrepreneurial organizations and observed a course for student filmmakers learning to make documentaries for social entrepreneurs. The findings of this study suggested that social entrepreneurs used documentary film as a communications tool when it aligned with their stated missions and goals but that cost, time, and control were significant barriers to implementation. Additionally, social entrepreneurs in all phases of development exhibited a unique set of cultural characteristics that interacted with the intent, content, and effect of their films in both positive and negative ways. The author also noted three distinct levels of filmmaker involvement with social entrepreneurial organizations that impacted the intent, content, and effect of their respective films. These levels of involvement are described as collaborative, independent, and interdependent. While the author offers some provocative observations about the role of documentary in social entrepreneurial organizations, this study remains exploratory in nature. She suggests several additional avenues of research that may further the scholarly conversation and continue to shed light on documentary film as communication for and by social entrepreneurs.

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.

With the generalization of Lean Burn combustors, the flow field entering the turbine tends to feature higher levels of swirl, turbulence, while different hot streak patterns often emerge if compared to the previous generation of combustion chambers. In this context, the combustor-turbine interactions and more specifically the transport of hot streaks through the turbine need to be further analysed to gain engine performance and improved turbine life. Considering this new context, a non-reactive axial combustor simulator representative of a Lean Burn architecture, together with a 1.5 high pressure turbine stage is developed within the European project FACTOR. The interaction between these two modules is numerically investigated by performing Large Eddy Simulation (LES) of the combustor simulator equipped with two Nozzle Guide Vanes (NGVs). By using such an integrated approach, the combustor-turbine interface (plane 40) disappears, allowing: (i) more realistic inlet conditions to the turbine by suppressing all the assumptions associated with averaged profiles; (ii) to account for the potential effect of the vanes on the chamber. Note that if compared to classical approaches, the use of time-resolved LES has the advantage of well predicting the combustor mean flow and turbulence, resulting in more realistic flow properties at the turbine inlet as confirmed by previous works on this configuration. This paper focuses first on two LESs of the combustor-turbine specific configurations: i.e., two clocking positions of the hot streak relative to the NGVs. Significant changes on the thermal field around the vanes are highlighted. When the hot streak is injected in front of a vane leading edge, it considerably heats up the pressure side compared to the adjacent vane although the temperature field is quite uniform at the NGV exit because of the enhanced mixing of the hot streak. On the other hand, when the hot streak is injected in the passage between two adjacent vanes, it remains away from the vane walls preventing them from heating up. The hot streak however crosses the vane passage without being significantly distorted resulting in a more heterogeneous flow field at the rotor inlet. Second, the potential effect induced by the presence of the vanes is investigated by comparing the flow field inside the chamber with and without NGVs. It is found that the potential effect does not alter temperature patterns while a significant radial and azimuthal mass flow redistribution is observed up to about 25% axial chord length upstream of the vanes. The turbulence level is affected by the presence of vanes up to plane 40 when the hot streak is aligned with the passage.