Radial Mass Density Research Articles

Control of Robot Motion in Radial Mass Density Field

T In this article, a new approach to control of robot motion in the radial mass density field is presented. This field is between the maximal and the minimal radial mass density values. Between these two limited values, one can use n points (n = 1, 2, . . . nmax) that can be included in the related algorithm for control of the robot motion. The number of the points nstep can be calculated by using the relation nstep = nmax / nvar , where nvar is the control parameter. The radial mass density is maximal at the minimal gravitational radius and minimal at the maximal gravitational radius. This is valid for Planck scale and for the scales that are less or higher of that one. Using the ratio of Planck mass and Planck radius it is generated the energy conservation constant κ = 0.99993392118.

Relativistic Radial Density Theory (RRDT)

Starting with Planck scale it is developed the Relativistic Radial Density Theory (RRDT). In this theory, the Planck and gravitational parameters can be described as the functions of the radial mass (energy) density value. This density is maximal at the minimal radius and minimal at the maximal radius. This conclusion is based on the fact that the ratio of Planck mass and Planck length (radius) is constant. These radiuses can be described as the function of the energy conservation constant κ. Using RRDT, it is possible to develop the connections between Planck’s and gravitational parameters as function of the maximal and minimal radial mass (energy) density values. In that sense, the gravitational length, time, energy and temperature can be presented as the function of the Planck length, time, energy and temperature, respectively. This opens possibility to merge of Quantum Field Theory (QFT) and the General Theory of Relativity (GTR) at the quantum scale in gravitational field. The existence of the maximal radial mass (energy) density value at the minimal radius in gravitational field means that no singularity in that field. Further, the existence of the minimal radial mass (energy) density value at the maximal radius in gravitational field means that no infinity in that field. It follows the postulation: the most minimal radius in a gravitational field belongs to the minimal mass (energy). Since the Planck mass is not the minimal mass in space-time, the Planck length/radius is not the minimal length/radius in the space-time. If the calculated minimal (or maximal) radius is the bigger than the related official radius it means that there exists a dark matter in this object. In that sense, the black holes are presenting the state of the matter at the minimal radius where we have the maximal radial mass (energy) density value. Further, the maximal possible radius of the matter is presenting the state with the minimal radial mass (energy) density value. Thus, the maximal and minimal radial mass (energy) density values are constants and conserved items. Now the question is: do motion of the Universe follows the RRDT?

TDCOSMO

Strong lensing time delays can measure the Hubble constant H0 independently of any other probe. Assuming commonly used forms for the radial mass density profile of the lenses, a 2% precision has been achieved with seven Time-Delay Cosmography (TDCOSMO) lenses, in tension with the H0 from the cosmic microwave background. However, without assumptions on the radial mass density profile – and relying exclusively on stellar kinematics to break the mass-sheet degeneracy – the precision drops to 8% with the current data obtained using the seven TDCOSMO lenses, which is insufficient to resolve the H0 tension. With the addition of external information from 33 Sloan Lens ACS (SLACS) lenses, the precision improves to 5% if the deflectors of TDCOSMO and SLACS lenses are drawn from the same population. We investigate the prospect of improving the precision of time-delay cosmography without relying on mass profile assumptions to break the mass-sheet degeneracy. Our forecasts are based on a previously published hierarchical framework. With existing samples and technology, 3.3% precision on H0 can be reached by adding spatially resolved kinematics of the seven TDCOSMO lenses. The precision improves to 2.5% with the further addition of kinematics for 50 nontime-delay lenses from SLACS and the Strong Lensing Legacy Survey. Expanding the samples to 40 time-delay and 200 nontime-delay lenses will improve the precision to 1.5% and 1.2%, respectively. Time-delay cosmography can reach sufficient precision to resolve the Hubble tension at 3–5σ, without assumptions on the radial mass profile of lens galaxies. By obtaining this precision with and without external datasets, we will test the consistency of the samples and enable further improvements based on even larger future samples of time-delay and nontime-delay lenses (e.g., from the Rubin, Euclid, and Roman Observatories).

The stellar mass function and evolution of the density profile of galaxy clusters from the Hydrangea simulations at 0 < z < 1.5

ABSTRACT Galaxy clusters are excellent probes to study the effect of environment on galaxy formation and evolution. Along with high-quality observational data, accurate cosmological simulations are required to improve our understanding of galaxy evolution in these systems. In this work, we compare state-of-the-art observational data of massive galaxy clusters ($\gt 10^{14}\, \textrm {M}_{\odot }$) at different redshifts (0 < z < 1.5) with predictions from the Hydrangea suite of cosmological hydrodynamic simulations of 24 massive galaxy clusters ($\gt 10^{14}\, \textrm {M}_{\odot }$ at z = 0). We compare three fundamental observables of galaxy clusters: the total stellar mass-to-halo mass ratio, the stellar mass function, and the radial mass density profile of the cluster galaxies. In the first two of these, the simulations agree well with the observations, albeit with a slightly too high abundance of $M_\star \lesssim 10^{10} \, \mathrm{M}_\odot$ galaxies at z ≳ 1. The Navarro–Frenk–White concentrations of cluster galaxies increase with redshift, in contrast to the decreasing dark matter (DM) halo concentrations. This previously observed behaviour is therefore due to a qualitatively different assembly of the smooth DM halo compared to the satellite population. Quantitatively, we, however, find a discrepancy in that the simulations predict higher stellar concentrations than observed at lower redshifts (z < 0.3), by a factor of ≈2. This may be due to selection bias in the simulations, or stem from shortcomings in the build-up and stripping of their inner satellite halo.

A thick-disk galaxy model and simulations of equal-mass galaxy pair collisions

We implement a numerical model reported in the literature to simulate the evolution of a galaxy composed of four matter components, such as: a dark-matter halo; a rotating disk of stars; a spherical bulge of stars and a ring of molecular gas. We show that the evolution of this galaxy model is stable at least for 10 Gyr (Gyr = 109 years). We characterize the resulting configuration of this galaxy model by figures of the circular velocity and angular momentum distribution; the tangential and radial components of the velocity; the peak density evolution and the radial density profile. Additionally, we calculate several models of equal-mass galaxy binary collisions, such as: (i) frontal and (ii) oblique (with an impact parameter), (iii) two models with initial conditions taken from a 2-body orbit and (iv) a very close passage. To allow comparison with the galaxy model, we characterize the dynamics of the collision models in an analogous way. Finally, we determine the de Vaucouleurs fitting curves of the radial density profile, on a radial scale of 0–100 kpc, for all the collision models irrespective of the pre-collision trajectory. To study the radial mass density and radial surface density profiles at a smaller radial scale, 0–20 kpc, we use a four-parameter fitting curve.

Tracing the anemic stellar halo of M 101

Models of galaxy formation in a cosmological context predict that massive disk galaxies should have structured extended stellar halos. Recent studies in integrated light, however, report that a few galaxies, including the nearby disk galaxy M 101, have no measurable stellar halos to the detection limit. We aim to quantify the stellar content and structure of M 101’s outskirts by resolving its stars. We present the photometry of its stars based on deepF606WandF814Wimages taken withHubbleSpace Telescope (HST) as part of the GHOSTS survey. The HST fields are placed along the east and west sides of M 101 out to galactocentric distance (R) of ∼70 kpc. The constructed color-magnitude diagrams of stars reach down to two magnitudes below the tip of the red giant branch. We derived radial number density profiles of the bright red giant branch (RGB) stars. The mean color of the RGB stars atR ∼ 40−60 kpc is similar to those of metal-poor globular clusters in the Milky Way. We also derived radial surface brightness profiles using the public image data provided by the Dragonfly team. Both the radial number density and surface brightness profiles were converted to radial mass density profiles and combined. We find that the mass density profiles show a weak upturn at the very outer region, where surface brightness is as faint asμg ≈ 33 mag arcsec−2. An exponential disk + power-law halo model on the mass density profiles finds the total stellar halo mass ofMhalo= 8.2−2.2+3.5× 107M⊙. The total stellar halo mass does not exceedMhalo = 3.2 × 108 M⊙when strongly truncated disk models are considered. In combining the halo mass with the total stellar mass of M 101, we obtain the stellar halo mass fraction ofMhalo/Mgal= 0.20−0.08+0.10% with an upper limit of 0.78%. We compare the halo properties of M 101 with those of six GHOSTS survey galaxies as well as the Milky Way and M 31 and find that M 101 has an anemic stellar halo similar to the Milky Way.

An Empirical Model for the Dayside Magnetospheric Plasma Mass Density Derived From EMMA Magnetometer Network Observations

AbstractA local time dependent empirical model of the equatorial plasma mass density in the inner magnetosphere is derived from field line resonance (FLR) observations at the European quasi‐Meridional Magnetometer Array (EMMA). Models of the plasmasphere, plasmatrough, and plasmapause are derived separately and then combined. The whole model is limited to the local time (LT) sector 06:00‐18:00 and to the range of equatorial distances . It is also dependent on the geomagnetic activity but only in determining the plasmapause position. It well describes the recovery phase following a plasmasphere erosion but is not intended to reproduce highly dynamical phases. The plasmasphere model is limited to the range and predicts a mass density increase in the daytime sector (10–18 LT) which becomes more evident with increasing (up to a factor of 2). A comparison with previous models of plasmaspheric electron density suggests that the diurnal variation is mainly contributed by the heavy ions. The plasmatrough model is limited to the range and predicts a diurnal variation even more pronounced. Comparison with electron density models suggests that the average ion mass density can increase from 2.0 to 4–5 amu during daytime hours. An automated algorithm to search for plasmapause signatures in the radial mass density profiles derived from experimental observations is also presented. It could represent a useful space weather tool when included in a real‐time monitoring system of the plasmasphere.

Solvent effect on the formation of NTO/TZTN cocrystal explosives

Solvents play a key role in the preparation of cocrystals of energetic materials. In order to understand the effect of solvent on crystal growth, we constructed interface models of 3-nitro-1,2,4-triazol-5-one (NTO)/5,6,7,8-tetrahydrotetrazolo[1,5-b] [1,2,4]-triazine (TZTN)-solutions in three different solvents, i.e. methanol, ethylacetate and acetone, and carried out quantum chemistry (QC) and molecular dynamics (MD) simulations. The results showed that NTO and TZTN are easier to be adsorbed on the growth surfaces than the solvent in the solution according to the results of the binding energy of NTO/TZTN-solution models. From the results of binding energy, radial distribution function (RDF) and mass density distribution, conclusion can be drawn that the interaction between main growth surfaces and the solute molecules, namely NTO and TZTN, was stronger in methanol solvent than in others. There was a positive cooperativity effects on the binding of NTO to TZTN in the presence of methanol, which might explain why NTO/TZTN cocrystals have been successfully prepared from methanol solvent. Our findings are expected to provide some guidelines for preparing and designing the cocrystal.

The Three Hundred Project: The evolution of galaxy cluster density profiles

Recent numerical studies of the dark matter density profiles of massive galaxy clusters ($M_{\rm halo} > 10^{15}$M$_{\odot}$) show that their median radial mass density profile remains unchanged up to $z > 1$, displaying a highly self-similar evolution. We verify this by using the data set of the THE THREE HUNDRED project, i.e. 324 cluster-sized haloes as found in full physics hydrodynamical simulations. We track the progenitors of the mass-complete sample of clusters at $z=0$, and find that their median shape is already in place by $z=2.5$. However, selecting a dynamically relaxed subsample ($\sim16$ per cent of the clusters), we observe a shift of the scale radius $r_s$ towards larger values at earlier times. Classifying the whole sample by formation time, this evolution is understood as a result of a two-phase halo mass accretion process. Early-forming clusters -- identified as relaxed today -- have already entered their slow accretion phase, hence their mass growth occurs mostly at the outskirts. Late-forming clusters -- which are still unrelaxed today -- are in their fast accretion phase, thus the central region of the clusters is still growing. We conclude that the density profile of galaxy clusters shows a profound self-similarity out to redshifts $z\sim2.5$. This result holds for both gas and total density profiles when including baryonic physics, as reported here for two rather distinct sub-grid models.

First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies

The IllustrisTNG project is a new suite of cosmological magneto-hydrodynamical simulations of galaxy formation performed with the Arepo code and updated models for feedback physics. Here we introduce the first two simulations of the series, TNG100 and TNG300, and quantify the stellar mass content of about 4000 massive galaxy groups and clusters ($10^{13} \leq M_{\rm 200c}/M_{\rm sun} \leq 10^{15}$) at recent times ($z \leq 1$). The richest clusters have half of their total stellar mass bound to satellite galaxies, with the other half being associated with the central galaxy and the diffuse intra-cluster light. The exact ICL fraction depends sensitively on the definition of a central galaxy's mass and varies in our most massive clusters between 20 to 40% of the total stellar mass. Haloes of $5\times 10^{14}M_{\rm sun}$ and above have more diffuse stellar mass outside 100 kpc than within 100 kpc, with power-law slopes of the radial mass density distribution as shallow as the dark matter's ( $-3.5 < \alpha_{\rm 3D} < -3$). Total halo mass is a very good predictor of stellar mass, and vice versa: at $z=0$, the 3D stellar mass measured within 30 kpc scales as $\propto (M_{\rm 500c})^{0.49}$ with a $\sim 0.12$ dex scatter. This is possibly too steep in comparison to the available observational constraints, even though the abundance of TNG less massive galaxies ($< 10^{11}M_{\rm sun}$ in stars) is in good agreement with the measured galaxy stellar mass functions at recent epochs. The 3D sizes of massive galaxies fall too on a tight ($\sim$0.16 dex scatter) power-law relation with halo mass, with $r^{\rm stars}_{\rm 0.5} \propto (M_{\rm 500c})^{0.53}$. Even more fundamentally, halo mass alone is a good predictor for the whole stellar mass profiles beyond the inner few kpc, and we show how on average these can be precisely recovered given a single mass measurement of the galaxy or its halo.

On the origin of the dawn‐dusk asymmetry of toroidal Pc5 waves

AbstractObservations in space and on the ground have shown that azimuthally polarized (toroidal) magnetospheric Pc5 waves (frequency = 1.7–6.7 mHz) are more prominent on the dawnside than on the duskside, but the origin of this dawn‐dusk asymmetry is unknown. To determine the origin, we conducted a statistical analysis of toroidal Pc5 waves at the Time History of Events and Macroscale Interactions during Substorms (THEMIS) D spacecraft using ion bulk velocity measured during 2008–2014. We found that both the detection rate of narrowband Pc5 waves, which are attributed to fundamental toroidal‐mode standing Alfvén waves, and the amplitude of velocity oscillations in the fixed Pc5 band exhibit a dawn‐dusk asymmetry consistent with previous studies regardless of whether the interplanetary magnetic field is directed along the Parker spiral or orthogonal to it. These results imply that the asymmetry originates within the magnetosphere, not from a dawn‐dusk asymmetry of the Kelvin‐Helmholtz instability on the magnetopause. Based on theoretical studies published previously and a global magnetohydrodynamic simulation, we propose that the asymmetry originates from the local time dependence of the radial mass density variation and the associated gradient of the frequency of standing Alfvén waves. The THEMIS data indicate that in the L range 8–12 the average gradient is smaller in the dusk sector than in the dawn sector. This will result in weaker field line resonance (FLR), and thus weaker toroidal Pc5 waves, in the dusk sector. Density structures associated with drainage plumes may also suppress FLR in the dusk sector.

Interplay between internal structure and optical properties of thermosensitive nanogels

The structural and optical properties of thermosensitive particles, nanogels, are studied by light scattering and refractometry as a function of temperature. Nanogels are composed of poly- N-Isopropopylacrylamide, a polymer that shrinks at temperatures higher than its lower critical solution temperature, 33 °C. The internal nanogel structure obtained by light scattering is well modeled by assuming a constant radial mass density profile convoluted with a Gaussian function. Moreover, we introduce a simple method that allows us to describe the measured temperature-dependent index of refraction of these complex nanoparticles by using their structural information, core dimension and external radius.

Characterization of an acoustic spherical cloak

We analyze the following particular cloaking problem: the cloaked region consists of a sphere of a homogeneous medium which is identical with the medium occupying the exterior background space; this sphere is surrounded by a cloaking medium occupying a spherical shell and consisting of material with parameters depending only on the radial variable r. For this very special case, we show that the problem of determining the three functions characterizing the cloaking medium, namely, the radial mass density, the tangential mass density, and the compressibility, reduces to solving a well defined inverse problem for the Schrödinger equation. In particular, a concrete procedure is introduced for determining two of the above three functions in terms of the radial mass density via the solution of a Riemann–Hilbert problem.

Study of gas-puff Z-pinches on COBRA

Gas-puff Z-pinch experiments were conducted on the 1 MA, 200 ns pulse duration Cornell Beam Research Accelerator (COBRA) pulsed power generator in order to achieve an understanding of the dynamics and instability development in the imploding and stagnating plasma. The triple-nozzle gas-puff valve, pre-ionizer, and load hardware are described. Specific diagnostics for the gas-puff experiments, including a Planar Laser Induced Fluorescence system for measuring the radial neutral density profiles along with a Laser Shearing Interferometer and Laser Wavefront Analyzer for electron density measurements, are also described. The results of a series of experiments using two annular argon (Ar) and/or neon (Ne) gas shells (puff-on-puff) with or without an on- (or near-) axis wire are presented. For all of these experiments, plenum pressures were adjusted to hold the radial mass density profile as similar as possible. Initial implosion stability studies were performed using various combinations of the heavier (Ar) and lighter (Ne) gasses. Implosions with Ne in the outer shell and Ar in the inner were more stable than the opposite arrangement. Current waveforms can be adjusted on COBRA and it was found that the particular shape of the 200 ns current pulse affected on the duration and diameter of the stagnated pinched column and the x-ray yield.

NONLINEAR EVOLUTION OF DARK MATTER SUBHALOS AND APPLICATIONS TO WARM DARK MATTER

We describe the methodology to include nonlinear evolution, including tidal effects, in the computation of subhalo distribution properties in both cold (CDM) and warm (WDM) dark matter universes. Using semi-analytic modeling, we include effects from dynamical friction, tidal stripping, and tidal heating, allowing us to dynamically evolve the subhalo distribution. We calibrate our nonlinear evolution scheme to the CDM subhalo mass function in the Aquarius N-body simulation, producing a subhalo mass function within the range of simulations. We find tidal effects to be the dominant mechanism of nonlinear evolution in the subhalo population. Finally, we compute the subhalo mass function for $m_\chi=1.5$ keV WDM including the effects of nonlinear evolution, and compare radial number densities and mass density profiles of subhalos in CDM and WDM models. We show that all three signatures differ between the two dark matter models, suggesting that probes of substructure may be able to differentiate between them.

Unit cell structure of water-filled monoolein into inverted hexagonal (H(II)) mesophase modeled by molecular dynamics.

The study investigates the unit cell structure of inverted hexagonal (H(II)) mesophase composed of monoolein (1-monoolein, GMO) and water using atomistic molecular dynamics methods without imposing any restraints on lipid and water molecules. Statistically meaningful and very contrast images of the radial mass density distribution, scrutinizing also the separate components water, monoolein, the polar headgroups of the lipids, the double bond, and the termini of the hydrocarbon chain (the tail), are obtained. The lipid/water interface structure is analyzed based on the obtained water density distribution, on the estimated number of hydrogen bonds per monoolein headgroup, and on the headgroup-water radial distribution functions. The headgroup mass density distribution demonstrates hexagonal shape of the monoolein/water interface that is well-defined at higher water/monoolein ratios. Water interacts with the headgroups by forming a three-layer diffusive mass density distribution, and each layer's shape is close to hexagonal, which is an indication of long-range structural interactions. It is found that the monoolein headgroups form a constant number of hydrogen bonds leaving an excessive amount of water molecules outside the first lipid coordination sphere. Furthermore, the quantity of water at the monoolein/water interface increases steadily upon extension of the unit cell, so the interface should have a very dynamic structure. Investigation of the hydrocarbon residues reveals high compression and well-expressed structuring of the tails. The tails form a very compressed and constrained structure of defined layers across the unit cell with properties corresponding to a more densely packed nonpolar liquid (oil). Due to the hexagonal shape the 2D packing frustration is constant and does not depend on the water content. All reported structural features are based on averaging of the atomic coordinates over the time-length of the simulation trajectories. That kind of processing allows the observation of the water/GMO interface shape and its stability and mobility at a time scale close to the ones of the intermolecular interactions.

Molecular dynamics simulations and free energy profile of Paracetamol in DPPC and DMPC lipid bilayers

Molecular dynamics (MD) simulations and biased MD simulation were carried out for the neutral form of Paracetamol inserted in fully hydrated dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) lipid bilayers. For comparison, fully hydrated DMPC and DPPC lipid bilayers were also simulated separately without Paracetamol. The simulation time for each system was 50 ns. At two concentrations of Paracetamol, various properties of the lipid bilayer such as area per lipid, order parameter, diffusion coefficient, radial distribution function, electrostatic potential, mass density and hydrogen bonds have been calculated. Also, the convergence in time of the free energy profile of the Paracetamol along a DPPC bilayer normal was calculated by umbrella sampling method. From the obtained results, it can be concluded that neutral form of Paracetamol shows a generally similar behaviour in DPPC and DMPC lipid bilayers. It was shown that the addition of Paracetamol causes a decrease in tail order parameter of both DPPC and DMPC lipid bilayers and the tail of Paracetamol adopts an inward orientation in the lipid bilayers. Also from the free energy profile, the high penetration barrier in the bilayer centre was determined. The behaviour of Paracetamol in different dosages in two types of lipid bilayer membranes, DPPC and DMPC has been investigated by MD simulation. For the neutral form of the drug, the best position in the membrane has been identified by free energy calculations.

A census of stellar mass in ten massive haloes atz~ 1 from the GCLASS Survey

We study the stellar mass content of massive haloes in the redshift range 0.86<z<1.34, by measuring: (1) The stellar mass in the central galaxy versus total dynamical halo mass. (2) The total stellar mass (including satellites) versus total halo mass. (3) The radial stellar mass and number density profiles for the ensemble halo. We use a Ks-band selected catalogue for the 10 clusters in the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS), with photometric redshifts and stellar masses measured from 11-band SED fitting. Combining the photometric catalogues with the deep spectroscopic component of GCLASS, we correct the cluster galaxy sample for interlopers. We also perform a dynamical analysis of the cluster galaxies to estimate the halo mass M200 for each cluster based on a measurement of its velocity dispersion. (1) We find that the central galaxy stellar mass fraction decreases with total halo mass, and that this is in reasonable quantitative agreement with measurements from abundance matching studies at z~1. (2) The total stellar mass fractions of these systems decrease with halo mass, indicating that lower mass systems are more efficient at transforming baryons into stars. We find the total stellar mass to be a good proxy for total halo mass, with a small intrinsic scatter. When we compare these results with literature measurements, we find that the stellar mass fraction at fixed halo mass shows no significant evolution in the range 0<z<1. (3) We measure a relatively high NFW concentration parameter c ~ 7 for the stellar mass distribution in these clusters. A simple model shows that the stellar mass content of GCLASS can evolve in typical distributions observed at lower redshifts if the clusters primarily accrete stellar mass onto the outskirts. [Abridged]

A LINK BETWEEN STAR FORMATION QUENCHING AND INNER STELLAR MASS DENSITY IN SLOAN DIGITAL SKY SURVEY CENTRAL GALAXIES

We study the correlation between galaxy structure and the quenching of star formation using a sample of SDSS central galaxies with stellar masses 9.75< log M_*/M_sun<11.25 and redshifts z<0.075. GALEX UV data are used to cleanly divide the sample into star-forming and quenched galaxies, and to identify galaxies in transition (the green valley). Despite a stark difference in visual appearance between blue and red galaxies, their average radial stellar mass density profiles are remarkably similar (especially in the outer regions) at fixed mass. The inner stellar mass surface density within a radius of 1 kpc, \Sigma_1, is used to quantify the growth of the bulge as galaxies evolve. When galaxies are divided into narrow mass bins, their distribution in the color-\Sigma_1 plane at fixed mass forms plausible evolutionary tracks. \Sigma_1 seems to grow as galaxies evolve through the blue cloud, and once it crosses a threshold value, galaxies are seen to quench at fixed \Sigma_1. The \Sigma_1 threshold for quenching grows with stellar mass, \Sigma_1 ~ M_*^{0.64}. However, the existence of some star-forming galaxies above the threshold \Sigma_1 implies that a dense bulge is necessary but not sufficient to quench a galaxy fully. This would be consistent with a two-step quenching process in which gas within a galaxy is removed or stabilized against star formation by bulge-driven processes (such as a starburst, AGN feedback, or morphological quenching), whereas external gas accretion is suppressed by separate halo-driven processes (such as halo gas shock heating). Quenching thus depends on an interplay between the inner structure of a galaxy and its surrounding dark matter halo, and lack of perfect synchrony between the two could produce the observed scatter in color vs. \Sigma_1. (Abridged)

Beryllium liner implosion experiments on the Z accelerator in preparation for magnetized liner inertial fusion

Multiple experimental campaigns have been executed to study the implosions of initially solid beryllium (Be) liners (tubes) on the Z pulsed-power accelerator. The implosions were driven by current pulses that rose from 0 to 20 MA in either 100 or 200 ns (200 ns for pulse shaping experiments). These studies were conducted in support of the recently proposed Magnetized Liner Inertial Fusion concept [Slutz et al., Phys. Plasmas 17, 056303 (2010)], as well as for exploring novel equation-of-state measurement techniques. The experiments used thick-walled liners that had an aspect ratio (initial outer radius divided by initial wall thickness) of either 3.2, 4, or 6. From these studies, we present three new primary results. First, we present radiographic images of imploding Be liners, where each liner contained a thin aluminum sleeve for enhancing the contrast and visibility of the liner's inner surface in the images. These images allow us to assess the stability of the liner's inner surface more accurately and more directly than was previously possible. Second, we present radiographic images taken early in the implosion (prior to any motion of the liner's inner surface) of a shockwave propagating radially inward through the liner wall. Radial mass density profiles from these shock compression experiments are contrasted with profiles from experiments where the Z accelerator's pulse shaping capabilities were used to achieve shockless (“quasi-isentropic”) liner compression. Third, we present “micro-Ḃ” measurements of azimuthal magnetic field penetration into the initially vacuum-filled interior of a shocked liner. Our measurements and simulations reveal that the penetration commences shortly after the shockwave breaks out from the liner's inner surface. The field then accelerates this low-density “precursor” plasma to the axis of symmetry.