Generalized radial profile of field-reversed configurations based on symmetrical properties

Context. Powerful active galactic nuclei (AGN) are supposed to play a key regulatory role on the evolution of their host galaxies by shaping the thermodynamic properties of their gas component. However, little is known as to the nature and the visibility timescale of the kinematical imprints of AGN-driven feedback. Gaining theoretical and observational insights into this subject is indispensable for a thorough understanding of the AGN-galaxy coevolution and could yield empirical diagnostics for the identification of galaxies that have experienced a major AGN episode in the past. Aims. We present an investigation of kinematical imprints of AGN feedback on the warm ionized gas medium (WIM) of massive early-type galaxies (ETGs). To this end, we take a two-fold approach that involves a comparative analysis of Hα velocity fields in 123 local ETGs from the CALIFA (Calar Alto Legacy Integral Field Area Survey) integral field spectroscopy survey with 20 simulated galaxies from high-resolution hydrodynamic cosmological SPHgal simulations. The latter were resimulated for two modeling setups, one with and another without AGN feedback. Methods. In order to quantify the effects of AGN feedback on gas kinematics, we measured three parameters that probe deviations from simple regular rotation by using the kinemetry package. These indicators trace the possible presence of distinct kinematic components in Fourier space (k3, 5/k1), variations in the radial profile of the kinematic major axis (σPA), and offsets between the stellar and gas velocity fields (Δϕ). These quantities were monitored in the simulations from a redshift 3 to 0.2 to assess the connection between black hole accretion history, stellar mass growth, and the kinematical perturbation of the WIM. Results. Observed local massive galaxies show a broad range of irregularities, indicating disturbed warm gas motions, which is irrespective of being classified via diagnostic lines as AGN or not. Simulations of massive galaxies with AGN feedback generally exhibit higher irregularity parameters than without AGN feedback, which is more consistent with observations. Besides AGN feedback, other processes like major merger events or infalling gas clouds can lead to elevated irregularity parameters, but they are typically of shorter duration. More specifically, k3, 5/k1 is most sensitive to AGN feedback, whereas Δϕ is most strongly affected by gas infall. Conclusions. We conclude that even if the general disturbance of the WIM velocity is not a unique indicator for AGN feedback, irregularity parameters that are high enough to be consistent with observations can only be reproduced in simulations with AGN feedback. Specifically, an elevated value for the deviation from simple ordered motion is a strong sign for previous events of AGN activity and feedback.

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Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption

Journal of Plasma Physics ◽

10.1017/s002237782000152x ◽

2021 ◽

Vol 87 (1) ◽

Author(s):

M. Hoppe ◽

L. Hesslow ◽

O. Embreus ◽

L. Unnerfelt ◽

G. Papp ◽

...

Keyword(s):

Radial Profile ◽

Spatiotemporal Analysis ◽

High Energy ◽

Synchrotron Emission ◽

Analytic Model ◽

Runaway Electrons ◽

Radial Density ◽

Radial Density Profile ◽

Argon Injection ◽

Seed Population

Synchrotron radiation images from runaway electrons (REs) in an ASDEX Upgrade discharge disrupted by argon injection are analysed using the synchrotron diagnostic tool Soft and coupled fluid-kinetic simulations. We show that the evolution of the runaway distribution is well described by an initial hot-tail seed population, which is accelerated to energies between 25–50 MeV during the current quench, together with an avalanche runaway tail which has an exponentially decreasing energy spectrum. We find that, although the avalanche component carries the vast majority of the current, it is the high-energy seed remnant that dominates synchrotron emission. With insights from the fluid-kinetic simulations, an analytic model for the evolution of the runaway seed component is developed and used to reconstruct the radial density profile of the RE beam. The analysis shows that the observed change of the synchrotron pattern from circular to crescent shape is caused by a rapid redistribution of the radial profile of the runaway density.

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Dynamical evolution of multiple-population globular clusters

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab223 ◽

2021 ◽

Vol 502 (3) ◽

pp. 4290-4304

Author(s):

Enrico Vesperini ◽

Jongsuk Hong ◽

Mirek Giersz ◽

Arkadiusz Hypki

Keyword(s):

Structural Properties ◽

Globular Clusters ◽

First Generation ◽

Radial Profile ◽

Dynamical Evolution ◽

Evolutionary Phase ◽

Dynamical Parameters ◽

Energy Equipartition

ABSTRACT We have carried out a set of Monte Carlo simulations to study a number of fundamental aspects of the dynamical evolution of multiple stellar populations in globular clusters with different initial masses, fractions of second generation (2G) stars, and structural properties. Our simulations explore and elucidate: (1) the role of early and long-term dynamical processes and stellar escape in the evolution of the fraction of 2G stars and the link between the evolution of the fraction of 2G stars and various dynamical parameters; (2) the link between the fraction of 2G stars inside the cluster and in the population of escaping stars during a cluster’s dynamical evolution; (3) the dynamics of the spatial mixing of the first-generation (1G) and 2G stars and the details of the structural properties of the two populations as they evolve toward mixing; (4) the implications of the initial differences between the spatial distribution of 1G and 2G stars for the evolution of the anisotropy in the velocity distribution and the expected radial profile of the 1G and 2G anisotropy for clusters at different stages of their dynamical history; and (5) the variation of the degree of energy equipartition of the 1G and the 2G populations as a function of the distance from the cluster’s centre and the cluster’s evolutionary phase.

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Electric field in the edge layer of field‐reversed configurations

Physics of Fluids B Plasma Physics ◽

10.1063/1.860378 ◽

1992 ◽

Vol 4 (10) ◽

pp. 3226-3240 ◽

Cited By ~ 5

Author(s):

Pi‐Ren Chiang ◽

Ming‐Yuan Hsiao

Keyword(s):

Electric Field ◽

Edge Layer ◽

Field Reversed Configurations

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Influence of measurement noise on the determination of the radial profile of the photoelastic coefficient in step-index optical fibers

Applied Optics ◽

10.1364/ao.52.008451 ◽

2013 ◽

Vol 52 (35) ◽

pp. 8451 ◽

Cited By ~ 6

Author(s):

Sophie Acheroy ◽

Patrick Merken ◽

Heidi Ottevaere ◽

Thomas Geernaert ◽

Hugo Thienpont ◽

...

Keyword(s):

Optical Fibers ◽

Radial Profile ◽

Measurement Noise ◽

Step Index

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Observed Boundary Layer Wind Structure and Balance in the Hurricane Core. Part I: Hurricane Georges

Journal of the Atmospheric Sciences ◽

10.1175/jas3745.1 ◽

2006 ◽

Vol 63 (9) ◽

pp. 2169-2193 ◽

Cited By ~ 101

Author(s):

Jeffrey D. Kepert

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Tropical Cyclone ◽

Radial Profile ◽

Lower Altitude ◽

Near Surface ◽

Wind Structure ◽

The Right ◽

Tropical Cyclone Boundary Layer ◽

Upper Boundary

Abstract The GPS dropsonde allows observations at unprecedentedly high horizontal and vertical resolution, and of very high accuracy, within the tropical cyclone boundary layer. These data are used to document the boundary layer wind field of the core of Hurricane Georges (1998) when it was close to its maximum intensity. The spatial variability of the boundary layer wind structure is found to agree very well with the theoretical predictions in the works of Kepert and Wang. In particular, the ratio of the near-surface wind speed to that above the boundary layer is found to increase inward toward the radius of maximum winds and to be larger to the left of the track than to the right, while the low-level wind maximum is both more marked and at lower altitude on the left of the storm track than on the right. However, the expected supergradient flow in the upper boundary layer is not found, with the winds being diagnosed as close to gradient balance. The tropical cyclone boundary layer model of Kepert and Wang is used to simulate the boundary layer flow in Hurricane Georges. The simulated wind profiles are in good agreement with the observations, and the asymmetries are well captured. In addition, it is found that the modeled flow in the upper boundary layer at the eyewall is barely supergradient, in contrast to previously studied cases. It is argued that this lack of supergradient flow is a consequence of the particular radial structure in Georges, which had a comparatively slow decrease of wind speed with radius outside the eyewall. This radial profile leads to a relatively weak gradient of inertial stability near the eyewall and a strong gradient at larger radii, and hence the tropical cyclone boundary layer dynamics described by Kepert and Wang can produce only marginally supergradient flow near the radius of maximum winds. The lack of supergradient flow, diagnosed from the observational analysis, is thus attributed to the large-scale structure of this particular storm. A companion paper presents a similar analysis for Hurricane Mitch (1998), with contrasting results.

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Equilibrium of field reversed configurations with rotation. I. One space dimension and one type of ion

Physics of Plasmas ◽

10.1063/1.1475683 ◽

2002 ◽

Vol 9 (7) ◽

pp. 3057-3067 ◽

Cited By ~ 16

Author(s):

Norman Rostoker ◽

Artan Qerushi

Keyword(s):

Space Dimension ◽

Field Reversed Configurations ◽

One Space Dimension

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Radial profile of neon 1s5atoms in a He-Ne active discharge and their lens effect on lasing at 6401 Å

IEEE Journal of Quantum Electronics ◽

10.1109/jqe.1969.1075672 ◽

1969 ◽

Vol 5 (1) ◽

pp. 21-29 ◽

Cited By ~ 17

Author(s):

L. Schlie ◽

J. Verdeyen

Keyword(s):

Radial Profile ◽

Lens Effect

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Study of Pumping Capacity of Pitched Blade Impellers

Acta Polytechnica ◽

10.14311/380 ◽

2002 ◽

Vol 42 (4) ◽

Author(s):

I. Fořt ◽

T. Jirout ◽

R. Sperling ◽

S. Jambere ◽

F. Rieger

Keyword(s):

Laser Doppler Anemometry ◽

Radial Profile ◽

Axial Flow ◽

Power Input ◽

Vessel Diameter ◽

Energetic Efficiency ◽

Turbulent Regime ◽

Flat Bottom ◽

Mean Velocity ◽

Liquid Suspensions

A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń) of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input) and the impeller pumping effect (impeller pumping capacity). It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances) than for blending miscible liquids in mixing (higher impeller off bottom clearances).

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