Search NASA⌕ Search

SEARCH · Search NASA

Results for “outflow”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Directly Driven Ion Outflow

We examine ionospheric outflows in the high altitude magnetospheric polar cap during the POLAR satellite's apogee on April 19, 1996 using the Thermal Ion Dynamics Experiment (TIDE) instrument. The elevated levels of O(+) observed in this pass may be due to the geophysical conditions during and prior to the apogee pass. In addition to the high abundance of O(+) relative to H(+), several other aspects of this data are noteworthy. We observe relationships between the density, velocity, and temperature which appear to be associated with perpendicular heating and the mirror force, rather than adiabatic expansion. The H(+) outflow is at a fairly constant flux which is consistent with being source limited by charge exchange at lower altitudes. Local centrifugal acceleration in the polar cap is found to be insufficient to account for the main variations we observe in the outflow velocity. The solar wind speed is high during this pass approximately 700 kilometers per second, and there are Alfve'n waves present in the solar wind such that the solar wind speed and IMF Bx are correlated. In this pass both the H(+) and O(+) outflow velocities correlate with both the solar wind speed and IMF fluctuations. Polar cap magnetometer and Hydra electron data show the same long period wave structure as found in the solar wind and polar cap ion outflow. In addition, the polar cap Poynting flux along the magnetic field direction correlates well with the H(+) temperature (R=0.84). We conclude that the solar wind can drive polar cap ion outflow particularly during polar squalls by setting up a parallel drop that is tens of eV which then causes the ion outflow velocity of O(+) and H(+), the electrons, and magnetic perturbations to vary in a similar fashion.

Elliott, H. A.↗
NASA NTRS2003

Correction to "Asian chemical Outflow to the Pacific in Spring: Origins, Pathways, and Budgets" by Isabelle Bey et al.

We analyze the Asian outflow of CO, ozone, and nitrogen oxides (NOx) to the Pacific in spring by using the GEOS-CHEM global three-dimensional model of tropospheric chemistry and simulating the Pacific Exploratory Mission-West (PEM-West B) aircraft mission in February-March 1994. The GEOS-CHEM model uses assimilated meteorological fields from the NASA Goddard Earth Observing System (GEOS). It reproduces relatively well the main features of tropospheric ozone, CO, and reactive nitrogen species observed in PEM-West B, including latitudinal and vertical gradients of the Asian pollution outflow over the western Pacific although simulated concentrations of CO tend to be too low (possibly because biogenic sources are underestimated). We use CO as a long-lived tracer to diagnose the processes contributing to the outflow. The highest concentrations in the outflow are in the boundary layer (0-2 km), but the strongest outflow fluxes are in the lower free troposphere (2-5 km) and reflect episodic lifting of pollution over central and eastern China ahead of eastward moving cold fronts. This frontal lifting, followed by westerly transport in the lower free troposphere, is the principal process responsible for export of both anthropogenic and biomass burning pollution from Asia. Anthropogenic emissions from Europe and biomass burning emissions from Africa make also major contributions to the Asian outflow over the western Pacific; European sources dominate in the lower troposphere north of 40 degrees N, while African sources are important in the upper troposphere at low latitudes. For the period of PEM-West B (February-March) we estimate that fossil fuel combustion and biomass burning make comparable contributions to the budgets of CO, ozone, and NO, in the Asian outflow. We find that 13% of NO, emitted in Asia is exported as NO, or PAN, a smaller fraction than for the United States because of higher aerosol concentrations that promote heterogeneous conversion of NOx to HNO3. Production and export of ozone from Asia in spring is much greater than from the United States because of the higher photochemical activity.

Bey, Isabelle↗
DOE OSTI2021

Kiloparsec-scale AGN outflows and feedback in merger-free galaxies

ABSTRACT Recent observations and simulations have challenged the long-held paradigm that mergers are the dominant mechanism driving the growth of both galaxies and supermassive black holes (SMBH), in favour of non-merger (secular) processes. In this pilot study of merger-free SMBH and galaxy growth, we use Keck Cosmic Web Imager spectral observations to examine four low-redshift (0.043 < z < 0.073) disc-dominated ‘bulgeless’ galaxies hosting luminous active galactic nucleus (AGN), assumed to be merger-free. We detect blueshifted broadened [O iii] emission from outflows in all four sources, which the $\mathrm{[O\, \small {III}]}$/$\rm {H}\beta$ ratios reveal are ionized by the AGN. We calculate outflow rates in the range $0.12{-}0.7~\rm {M}_{\odot }~\rm {yr}^{-1}$, with velocities of $675{-}1710~\rm {km}~\rm {s}^{-1}$, large radial extents of $0.6{-}2.4~\rm {kpc}$, and SMBH accretion rates of $0.02{-}0.07~\rm {M}_{\odot }~\rm {yr}^{-1}$. We find that the outflow rates, kinematics, and energy injection rates are typical of the wider population of low-redshift AGN, and have velocities exceeding the galaxy escape velocity by a factor of ∼30, suggesting that these outflows will have a substantial impact through AGN feedback. Therefore, if both merger-driven and non-merger-driven SMBH growth lead to co-evolution, this suggests that co-evolution is regulated by feedback in both scenarios. Simulations find that bars and spiral arms can drive inflows to galactic centers at rates an order of magnitude larger than the combined SMBH accretion and outflow rates of our four targets. This work therefore provides further evidence that non-merger processes are sufficient to fuel SMBH growth and AGN outflows in disc galaxies.

Smethurst, R. J. (ORCID:0000000164177196)↗
DOE OSTI2021

Connecting Galactic Outflows and Star Formation: Inferences from Hα Maps and Absorption-line Spectroscopy at 1 ≲ z ≲ 1.5

We investigate the connection between galactic outflows and star formation using two independent data sets covering a sample of 22 galaxies between 1 ≲ z ≲ 1.5. The Hubble Space Telescope WFC3/G141 grism provides low spectral resolution, high spatial resolution spectroscopy yielding Hα emission-line maps from which we measure the spatial extent and strength of star formation. In the rest-frame near-UV, Keck/DEIMOS observes Fe ii and Mg ii interstellar absorption lines, which provide constraints on the intensity and velocity of the outflows. We compare outflow properties from individual and composite spectra with the star formation rate (SFR) and SFR surface density (Σ{sub SFR}), as well as the stellar mass and specific SFR (sSFR). The Fe ii and Mg ii equivalent widths (EWs) increase with both SFR and Σ{sub SFR} at ≳3σ significance, while the composite spectra show larger Fe ii EWs and outflow velocities in galaxies with higher SFR, Σ{sub SFR}, and sSFR. Absorption-line profiles of the composite spectra further indicate that the differences between subsamples are driven by outflows rather than the interstellar medium. While these results are consistent with those of previous studies, the use of Hα images makes them the most direct test of the relationship between star formation and outflows at z > 1 to date. Future facilities such as the James Webb Space Telescope and the upcoming Extremely Large Telescopes will extend these direct, Hα-based studies to lower masses and SFRs, probing galactic feedback across orders of magnitude in galaxy properties and augmenting the correlations we find here.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

CLASSY. VI. The Density, Structure, and Size of Absorption-line Outflows in Starburst Galaxies

Galaxy formation and evolution are regulated by the feedback from galactic winds. Absorption lines provide the most widely available probe of winds. However, since most data only provide information integrated along the line of sight, they do not directly constrain the radial structure of the outflows. In this paper, we present a method to directly measure the gas electron density in outflows (n e ), which in turn yields estimates of outflow cloud properties (e.g., density, volume filling factor, and sizes/masses). We also estimate the distance (r n ) from the starburst at which the observed densities are found. We focus on 22 local star-forming galaxies primarily from the COS Legacy Archive Spectroscopic SurveY (CLASSY). In half of them, we detect absorption lines from fine-structure excited transitions of Si $\tiny{II}$ (i.e., Si $\tiny{II}$ * ). We determine n e from relative column densities of Si $\tiny{II}$ and Si $\tiny{II}$ * , given Si $\tiny{II}$ * originates from collisional excitation by free electrons. We find that the derived n e correlates well with the galaxy's star formation rate per unit area. From photoionization models or assuming the outflow is in pressure equilibrium with the wind fluid, we get r n ~ 1–2r * or ~5r * , respectively, where r * is the starburst radius. Based on comparisons to theoretical models of multiphase outflows, nearly all of the outflows have cloud sizes large enough for the clouds to survive their interaction with the hot wind fluid. Most of these measurements are the first ever for galactic winds detected in absorption lines and, thus, will provide important constraints for future models of galactic winds.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1990

A numerical study of the outflow layer of tropical cyclones

Numerical simulations of idealized tropical cyclones with special emphasis on the outflow layer are presented. The quasi-steady state outflow layers of weak and strong cyclones are found to exhibit similar characteristics. The circulations are anticyclonic and asymmetric about the center; the outflow layer is dominated by a narrow, elongated outflow-jet contributing up to 50 percent of the angular momentum transport; the air particles in the outflow jet mostly originate from the lower level. Secondary circulations are found to influence the relative humidity and the potential vorticity at the outflow levels. In order to study the effect of upper tropospheric forcings, two variational numerical experiments using cumulus convection as the major link between the upper-level forcing and the tropical cyclone's response are conducted.

Shi, Jainn-Jong↗
NASA NTRS1994

The role of radiative acceleration in outflows from broad absorption line QSOs. 1: Comparison with O star winds

We investigate the role of radiation pressure in accelerating the broad absorption line (BAL) outflows in QSOs by comparing their properties with those of radiatively driven O star winds. We find that, owing to their lower column densities and higher velocity spreads, BAL outflows have only a few tens of strong resonance lines that are dynamically important, as compared with 10(exp 3) - 10(exp 4) lines in O star winds. We show that the combined radiative force (the 'force multiplier') declines more rapidly as a function of column density for BAL outflows than for O star winds. This is mainly attributed to the absence of lines from excited states in the BAL region. The absorbing gas in BAL outflows must have a small filling factor in order for radiative acceleration to be important dynamically. This allows the absorbing material to remain at a high enough density to maintain the ion species necessary for efficient radiative acceleration as well (as those responsible for the observed absorption), without the average flow density becoming so large that the absorbing matter cannot be accelerated by an increment larger than its own sound speed. The latter condition is necessary if the outflow is to tap a large portion of the incident photon momentum. Once a small filling factor is assumed, radiative acceleration can be more efficient in BAL outflows than in O stars. We show that terminal velocities of a few times 10(exp 4) km/sec can be expected, provided that the absorbing matter does not have to drag with it a much heavier substrate.

Arav, Nahum↗
NASA NTRS1995

Grain formation around carbon stars. 1: Stationary outflow models

Asymptotic giant branch (AGB) stars are known to be sites of dust formation and undergo significant mass loss. The outflow is believed to be driven by radiation pressure on grains and momentum coupling between the grains and gas. While the physics of shell dynamics and grain formation are closely coupled, most previous models of circumstellar shells have treated the problem separately. Studies of shell dynamics typically assume the existence of grains needed to drive the outflow, while most grain formation models assume a constant veolcity wind in which grains form. Furthermore, models of grain formation have relied primarily on classical nucleation theory instead of using a more realistic approach based on chemical kinetics. To model grain formation in carbon-rich AGB stars, we have coupled the kinetic equations governing small cluster growth to moment equations which determine the growth of large particles. Phenomenological models assuming stationary outflow are presented to demonstrate the differences between the classical nucleation approach and the kinetic equation method. It is found that classical nucleation theory predicts nucleation at a lower supersaturation ratio than is predicted by the kinetic equations, resulting in significant differences in grain properties. Coagulation of clusters larger than monomers is unimportant for grain formation in high mass-loss models but becomes more important to grain growth in low mass-loss situations. The properties of the dust grains are altered considerably if differential drift velocities are ignored in modeling grain formation. The effect of stellar temperature, stellar luminosity, and different outflow velocities are investigated. The models indicate that changing the stellar temperature while keeping the stellar luminosity constant has little effect on the physical parameters of the dust shell formed. Increasing the stellar luminosity while keeping the stellar temperature constant results in large differences in grain properties. For small outflow velocities, grains form at lower supersaturation ratios and close to the stellar photosphere, resulting in larger but fewer grains. The reverse is true when grains form under high outflow velocities, i.e., they form at higher supersaturation ratios, farther from the star, and are much smaller but at larger quantities.

Egan, Michael P.↗
NASA NTRS1995

Formation of Hydrocarbons in the Outflows from Red Giants

The formation of hydrocarbons in the oxygen-rich outflows from red giants was studied. The existence of organic molecules in such outflows has been known for several years; however, their surprisingly high abundances has been a mystery since all of the carbon had been thought to be irretrievably locked up in CO, the most strongly bound molecule. CO is the first molecule to form from the atoms present in the star's extended atmosphere, and as strong stellar winds drive a cooling outflow, dust grains condense out. In oxygen-rich outflows, the dust is thought to be composed mainly of silicates and other metal oxides. Perhaps the noble metals can condense out in metallic form, in particular the relatively abundant transition metals iron and nickel. We proposed that perhaps the carbon reservoir held as CO can be accessed through a catalytic process involving the chemisorption of CO and H2 onto grains rich in metallic iron. CO and H2 are the two most abundant molecules in circumstellar outflows, and they both are known to dissociate on transition metal surfaces at elevated temperatures, freeing carbon to form organic molecules such as methane. We believe methane is a precursor molecule to the organics observed in oxygen-rich red giants. We have developed a nonequilibrium numerical model of a surface chemical (catalytic) process. Based on this model, we believe that methane can be formed under the conditions present in circumstellar outflows. Although the methane formation rates are exceptionally low under these conditions, over dynamical timescales, a significant amount of CO can be converted to methane and driven further out in the envelope, explaining the presence of organics there.

Roberge, Wayne↗
NASA NTRS1996

Chemical Characteristics of Continental Outflow from Asia to the Troposphere over the Western Pacific Ocean during September - October 1991: Results from PEM-West A

An important objective of the Pacific Exploratory Mission-West A (PEM-West A) was the chemical characterization of the outflow of tropospheric trace gases and aerosol particles from the Asian continent over the western Pacific Ocean. This paper summarizes the chemistry of this outflow during the period September - October 1991. The vertical distributions of CO, C2H6, and NO(x), showed regions of outflow at altitudes below 2 km and from 8 to 12 km. Mixing ratios of CO were approx. equals 130 parts per billion by volume (ppbv), approx. equals 1OOO parts per trillion by volume (pptv) for C2H6, and approx. equals 100 pptv for NO(x) in both of these regions. Direct outflow of Asian industrial materials was clearly evident at altitudes below 2 km, where halocarbon tracer compounds such as CH3CCl3 and C2Cl4 were enhanced about threefold compared to aged Pacific air. The source attribution of species outflowing from Asia to the Pacific at 8-12 km altitude was not straightforward. Above 10 km altitude there were substantial enhancements of NO(y), O3, CO, CH4, SO2, C2H6, C3H8, C2H2, and aerosol Pb-210 but not halocarbon industrial tracers. These air masses were rich in nitrogen relative to sulfur and contained ratios of C2H2/CO and C3H8/C2H6 (approx. equals l.5 and 0.1 respectively) indicative of several- day-old combustion emissions. It is unclear if these emissions were of Asian origin, or if they were rapidly transported to this region from Europe by the high wind speeds in this tropospheric region (60 - 70 m/s). The significant cyclonic activity over Asia at this time could have transported to the upper troposphere emissions from biomass burning in Southeast Asia or emissions from the extensive use of various biomass materials for cooking and space heating. Apparently, the emissions in the upper troposphere were brought there by wet convective systems since water-soluble gases and aerosols were depleted in these air masses. Near 9 km altitude there was a distinct regional outflow that appeared to be heavily influenced by biogenic processes on the Asian continent, especially from the southeastern area. These air masses contained CH4 in excess of 1800 ppbv, while CO2 and OCS were significantly depleted (349 - 352 ppmv and 450 - 500 pptv, respectively). This signature seemingly reflected CH4 emissions from wetlands and rice paddies with coincident biospheric uptake of tropospheric CO2 and OCS.

Talbot, R. W.↗
NASA NTRS2000

Cloud Microphysics in Hurricane Outflows: Observations in 'Bonnie' (1998) at 12 km Altitude

The water balance of a hurricane is controlled by boundary layer inflow, near vertical motion in the eyewall causing coalescence precipitation at above and residual ice precipitation at below freezing temperatures, and cirrus outflow at below -40 C aloft. In this paper we address the question of efficiency of water removal by this cirrus outflow which is important for the release of latent heat at high altitudes and its role in the dynamic flow at that level. During NASA's 1998 Convection and Moisture Experiment campaign we acquired microphysical outflow data in order to (1) determine the release and redistribution of latent heat near the top of hurricanes, (2) aid in TRMM algorithm development for remote sensing of precipitation, and (3) determine the optical/radiative characteristics of hurricane outflow. The data were acquired with Particle Measuring Systems two dimensional imaging spectrometers. On 23 August and again during the hurricane's landfall on 26 August, 1998, the NASA DC-8 aircraft penetrated hurricane 'Bonnie' four times each near 200 hPa pressure altitude. The eye crossing times were determined by (1) zero counts of cloud particles, (2) approximately 5 C increases in static and potential temperatures, and (3) minima in speeds and changes of direction of horizontal winds. The vertical winds showed shear between -6 m per second and +4 m per second and tangential winds approached 30 m per second in the eyewall. The particle volumes in the eyewall (determined by the pixels the particles shadowed in the direction of flight [x-direction] and normally to it by the number of diodes that they shadowed [y-direction]) ranged between 0.5 and 5.0 cubic centimeters per cubic meter. With a particle density near 0.2 g per cubic centimeter (determined from in situ melting and evaporation on a surface collector), the 1.0 g per meter corresponding mass of cloud ice ranged between 0.27 and 2.7 g per kilograms yielding horizontal fluxes between 8.1 and 81 g per square meters per second. The outflow ice was concentrated in crystals of a modal size of 190 micrometers. The particle size distributions were heavily skewed toward sizes with 98% of all cirrus particles smaller than the modal size comprising, however, only 20% of the mass. Thus the smaller than modal size particles dominantly affected the optical/radiative characteristics of the cloud, whereas the larger than modal size crystals determined the ice mass, hence dominated latent heating. Questions to be addressed relate to the origin of individual ice particles as the hurricane evolved and the likelihood of pristine and aggregate particle formation under the complicated conditions of rotation and outflow in the eyewall.

Pueschel, Rudolf F.↗
NASA NTRS2011

X-Ray Evidence for the Accretion Disc-Outflow Connection in 3C 111

We present the spectral analysis of three Suzaku X-ray Imaging Spectrometer observations of 3C III requested to monitor the predicted variability of its ultrafast outflow on approximately 7 d time-scales. We detect an ionized iron emission line in the first observation and a blueshifted absorption line in the second, when the flux is approximately 30 per cent higher. The location of the material is constrained at less than 0.006 pc from the variability. Detailed modelling supports an identification with ionized reflection off the accretion disc at approximately 20-100rg from the black hole and a highly ionized and massive ultrafast outflow with velocity approximately 0.1c, respectively. The outflow is most probably accelerated by radiation pressure, but additional magnetic thrust cannot be excluded. The measured high outflow rate and mechanical energy support the claims that disc outflows may have a significant feedback role. This work provides the first direct evidence for an accretion disc-outflow connection in a radio-loud active galactic nucleus, possibly linked also to the jet activity.

Tombesi, Frank↗
NASA NTRS2022

A 30kpc Spatially Extended Clumpy and Asymmetric Galactic Outflow atz∼1.7

We image the spatial extent of a cool galactic outflow with fine-structure Fe ii* emission and resonant Mg ii emission in a gravitationally lensed star-forming galaxy at z = 1.70347. The Fe ii* and Mg ii (continuum-subtracted) emissions span out to radial distances of ∼14.33 and 26.5 kpc, respectively, with maximum spatial extents of ∼21 kpc for Fe ii* emission and ∼30 kpc for Mg ii emission. Mg ii emission is patchy and covers a total area of ∼184 kpc2, constraining the minimum area covered by the outflowing gas to be ∼13% of the total area. Mg ii emission is asymmetric and shows ∼21% more extended emission along the decl. direction. We constrain the covering fractions of the Fe ii* and Mg ii emission as a function of radial distance and characterize them with a power-law model. The Mg ii 2803 emission line shows two kinematically distinct emission components and may correspond to two distinct shells of outflowing gas with a velocity separation of Δv ∼ 400 km s−1. By using multiple images with different magnifications of the galaxy in the image plane, we trace the Fe ii* and Mg ii emissions around three individual star-forming regions. In all cases, both the Fe ii* and Mg ii emissions are more spatially extended compared to the star-forming regions traced by the [O ii] emission. These findings provide robust constraints on the spatial extent of the outflowing gas and, combined with outflow velocity and column density measurements, will give stringent constraints on mass-outflow rates of the galaxy.

Ahmed Shaban↗
NASA NTRS2023

MAXI J1848-015: The first detection of relativistically moving outflows from a globular cluster X-ray binary

Over the past decade, observations of relativistic outflows from outbursting X-ray binaries in the Galactic field have grown significantly. In this work, we present the first detection of moving and decelerating radio-emitting outflows from an X-ray binary in a globular cluster. MAXI J1848−015 is a recently discovered transient X-ray binary in the direction of the globular cluster GLIMPSE-C01. Using observations from the Karl G. Jansky Very Large Array, and a monitoring campaign with the MeerKAT observatory for 500 days, we model the motion of the outflows. This represents some of the most intensive, long-term coverage of relativistically moving X-ray binary outflows to date. We use the proper motions of the outflows from MAXI J1848−015 to constrain the component of the intrinsic jet speed along the line of sight, βint COS θejection, to be =0.19 ± 0.02. Assuming it is located in GLIMPSE-C01, at 3.4 kpc, we determine the intrinsic jet speed, βint = 0.79 ± 0.07, and the inclination angle to the line of sight, θejection = 76° ± 2°. This makes the outflows from MAXI J1848−015 somewhat slower than those seen from many other known X-ray binaries. We also constrain the maximum distance to MAXI J1848−015 to be 4.3 kpc. Finally, we discuss the implications of our findings for the nature of the compact object in this system, finding that a black hole primary is a viable (but as-of-yet unconfirmed) explanation for the observed properties of MAXI J1848−015. If future data and/or analysis provide more conclusive evidence that MAXI J1848−015 indeed hosts a black hole, it would be the first black hole X-ray binary in outburst identified in a Galactic globular cluster.

A. Bahramian↗
DOE OSTI2022

Non-Gaussianity of optical emission lines in SDSS star-forming galaxies and its implications on galactic outflows

The shape of emission lines in the optical spectra of star-forming galaxies reveals the kinematics of the diffuse gaseous component. We analyse the shape of prominent emission lines in a sample of ~ 53000 star-forming galaxies from the Sloan Digital Sky Survey, focusing on departures from gaussianity. Departures from a single gaussian profile allow us to probe the motion of gas and to assess the role of outflows. The sample is divided into groups according to their stellar velocity dispersion and star formation rate (SFR). The spectra within each group are stacked to improve the signal-to-noise ratio of the emission lines, to remove individual signatures, and to enhance the effect of SFR on the shapes of the emission lines. The moments of the emission lines, including kurtosis and skewness, are determined. We find that most of the emission lines in strong star-forming systems unequivocally feature negative kurtosis. This signature is present in Hβ, Hα, [N ii], and [S ii] in massive galaxies with high SFRs. We attribute it as evidence of radial outflows of ionised gas driven by the star formation of the galaxies. Also, most of the emission lines in low-mass systems with high SFRs feature negative skewness, and we interpret it as evidence of dust obscuration in the galactic disk. These signatures are however absent in the [O iii] line, which is believed to trace a different gas component. The observed trend is significantly stronger in face-on galaxies, indicating that star formation drives the outflows along the galactic rotation axis, presumably the path of least resistance. The data suggest that outflows driven by star formation exert accumulated impacts on the interstellar medium, and the outflow signature is more evident in older galaxies as they have experienced a longer total duration of star formation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

The impact of environmental effects on active galactic nuclei: A decline in the incidence of ionized outflows

Active galactic nuclei (AGNs) have generally been considered to be less frequent in denser environments due to a lower number of galaxy-galaxy interactions and/or the removal of their gas-rich reservoirs by the dense intergalactic medium. However, recent observational and theoretical works suggest that the effect of ram-pressure stripping acting on galaxies in dense environments might reduce the angular momentum of their gas, causing it to infall towards the super massive black hole at their centre, activating the AGN phase. In this work we explore the connection between environment and nuclear activity by evaluating the variation in the incidence of ionized outflows, a common phenomenon associated with nuclear activity, in AGNs across different environments. We select a sample of approximately 3300 optical AGNs from the Sloan Digital Sky Survey Data Release 13, which we match with a group catalogue to identify galaxies in isolation or residing in groups. We further probe their environments through the projected distance to the central galaxy of the group or cluster and the projected surface density to the fifth neighbour (δ 5 ). The presence of ionized outflows is determined through the modelling of the [O III] λ5007 emission line. We find that at lower masses (< 10 10.3 M ⊙ ), the fraction of ionized outflows is significantly lower in satellite AGNs (~7%) than in isolated (~22%) AGNs, probably due to their different AGN luminosity, L [O III] , in this stellar mass range. The fraction of outflows decreases at distances closer to the central galaxy of the group or cluster for all satellite AGNs; however, only the lower-mass ones (10 9 - 10 10.3 M ⊙ ) display a significant decline with δ 5 . Although this study does not include AGNs in the densest regions of galaxy clusters, our findings suggest that AGNs in dense environments accrete less gas than those in the field, potentially due to the removal of the gas reservoirs via stripping or starvation, leading to a negative connection between environment and AGN activity. Based on our results, we propose that the observed change in the incidence of outflows when moving towards denser regions of groups and clusters could contribute to the higher gas metallicities of cluster galaxies compared to field galaxies, especially at lower masses.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Delving into the depths of NGC 3783 with XRISM V. Broad-band modelling of ionized outflows

The Seyfert 1 galaxy NGC 3783 hosts a multi-phase warm absorber (WA) that has been extensively studied in the X-ray band. High-resolution spectra from 2000−2001 revealed a complex outflow with multiple ionization and velocity components. Two decades later, new XMM-Newton and XRISM observations allow us to investigate the long-term evolution of these outflows. We performed joint spectral modelling of the XMM-Newton /RGS and XRISM/Resolve time-averaged spectra using the pion photoionization code within SPEX. We derived the ionization parameter, column density, turbulent velocity, and outflow velocity for each absorption component, and investigated their thermal stability and absorption measure distribution (AMD) to characterize the physical and dynamical properties of the WA in NGC 3783 in 2024. We compared these results with the 2000−2001 epoch to assess long-term variability, stability, and possible changes in the absorber population. We identify eight WA components spanning log ξ = 1.08 − 3.38 and outflow velocities of 480−1230 km s −1 . The ranges of column densities and turbulent velocities remain broadly consistent with the WAs from 2000−2001, but the earlier data contained more low-ionization, high-velocity components. The total column density of all the outflows in 2024 is 1.5 times larger than in 2000−2001, which means that it has been replenished by fresh material. The dominant unresolved transition array (UTA) absorber (component B3) has increased its column density by a factor of three while maintaining a similar ionization parameter. The WAs in NGC 3783 have undergone significant structural and dynamical evolution over the past 24 years.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Bipolar planetary nebulae from outflow collimation by common envelope evolution

ABSTRACT The morphology of bipolar planetary nebulae (PNe) can be attributed to interactions between a fast wind from the central engine and the dense toroidal-shaped ejecta left over from common envelope (CE) evolution. Here we use the 3D hydrodynamic adaptive mesh refinement (AMR) code AstroBEAR to study the possibility that bipolar PN outflows can emerge collimated even from an uncollimated spherical wind in the aftermath of a CE event. The output of a single CE simulation via the smoothed particle hydrodynamics (SPH) code phantom serves as the initial conditions. Four cases of winds, all with high enough momenta to account for observed high momenta pre-PN outflows, are injected spherically from the region of the CE binary remnant into the ejecta. We compare cases with two different momenta and cases with no radiative cooling versus application of optically thin emission via a cooling curve to the outflow. Our simulations show that in all cases highly collimated bipolar outflows result from deflection of the spherical wind via the interaction with the CE ejecta. Significant asymmetries between the top and bottom lobes are seen in all cases. The asymmetry is strongest for the lower momentum case with radiative cooling. While real post-CE winds may be aspherical, our models show that collimation via ‘inertial confinement’ will be strong enough to create jet-like outflows even beginning with maximally uncollimated drivers. Our simulations reveal detailed shock structures in the shock-focused inertial confinement (SFIC) model and develop a lens-shaped inner shock that is a new feature of SFIC-driven bipolar lobes.

79 ASTRONOMY AND ASTROPHYSICS↗