Angular Momentum Profile Research Articles

Particle dynamics with trajectories and epicyclic oscillations around a piece-wise black hole immersed in dark matter

We investigate the dynamics of neutral test particles revolving around a non-rotating black hole immersed in dark matter DM. We derive exact solutions for the radial profiles of specific angular momentum and energy for equatorial stable circular orbits as a function of the parameters of the black hole. Using the effective potential approach, we explore the stability of these circular orbits and the effective force acting on particles in the presence of dark matter. Additionally, we examine the impact of dark matter on the innermost stable circular orbits. By numerically integrating the equations of motion, we plot the trajectories of particles around the black hole and analyze how dark matter affects these trajectories. We also calculate the analytical frequencies of radial and latitudinal harmonic oscillations as functions of the dark matter parameter for both local and distant observers. We compare these results with scenarios where dark matter is absent. Furthermore, we study the effects of dark matter on periastron precession. We present an analysis of the constraints on the dark matter and black hole mass parameters using Markov Chain Monte Carlo (MCMC) methods. Our study focuses on QPOs observed in X-ray binaries, in particular, the microquasars GRO J1655-40 and XTE J1550-564, and the centers of the galaxies M82 X-1 and Sgr A⁎. We also analyze the particle collisions, discussing the center-of-mass energy of the colliding particles. Our observations reveal that the motion of particles revolving around the black hole is significantly affected by varying the model parameters.

Observational signature of QPOs with particle motion around non-commutative Schwarzschild black hole surrounded by perfect fluid dark matter

We analyze the orbital and oscillatory motion of test particles in the vicinity of a non-commutative black hole submerged in perfect fluid dark matter and derive analytical solutions for the specific angular momentum and radial profiles of energy. Using the effective potential approach, we discuss the stability of circular orbits. Furthermore, we calculate the innermost stable circular orbits. The effective force acting on particles has also been discussed. We find the expressions for frequencies of radial and latitudinal harmonic oscillations as a function of the black hole mass and the model’s parameters. The key features of quasi-periodic oscillations of test particles near the stable circular orbits in an equatorial plane of the black hole are discussed. Furthermore, Periastron precession has been discussed. We demonstrate that the parameters of the model have a strong influence on particle motion around black holes. By using the observational data of four different X-ray binary systems GRO J1655-40, XTE J1550-564, XTE J1859+226, and GRS 1915+105, within the scope of Monte Carlo Markov Chain, we constrain the involved parameters α and β. It is necessary to mention that our presented investigations through graphical behavior are viable with required physical behavior.

Protostellar Disk Formation Regimes: Angular Momentum Conservation versus Magnetic Braking

Protostellar disks around young protostars exhibit diverse properties, with their radii ranging from less than ten to several hundred astronomical units. To investigate the mechanisms shaping this disk radius distribution, we compiled a sample of 27 Class 0 and I single protostars with resolved disks and dynamically determined protostellar masses from the literature. Additionally, we derived the radial profile of the rotational-to-gravitational-energy ratio in dense cores from the observed specific angular momentum profiles in the literature. Using these observed protostellar masses and rotational energy profile, we computed theoretical disk radii from the hydrodynamic and nonideal magnetohydrodynamic (MHD) models in Y.-N. Lee et al. and generated synthetic samples to compare with the observations. In our theoretical model, the disk radii are determined by hydrodynamics when the central protostar+disk mass is low. After the protostars and disks grow and exceed certain masses, the disk radii become regulated by magnetic braking and nonideal MHD effects. The synthetic disk radius distribution from this model matches well with the observations. This result suggests that hydrodynamics and nonideal MHD can be dominant in different mass regimes (or evolutionary stages), depending on the rotational energy and protostar+disk mass. This model naturally explains the rarity of large (>100 au) disks and the presence of very small (<10 au) disks. It also predicts that the majority of protostellar disks have radii of a few tens of astronomical units, as observed.

GRMHD Simulations of Accretion Structures with Different Angular Momentum Profiles

In this article, we explore the dynamics of accretion structures encircling spherically symmetric black holes, comparing three accretion disk models with distinct angular momentum profiles: (i) the geometrically thin Keplerian disk, (ii) the Fishbone–Moncrief torus; and (iii) the Polish Doughnut. Employing general relativistic magnetohydrodynamics simulations with the High Accuracy Relativistic Magnetohydrodynamics code, we investigate these three models, considering the magnetic field’s influence on the accretion disk angular momentum redistribution. We show that the magnetic field is a key factor in accretion disk structures, especially in regions with lower mass density. Our investigation verifies the well-established fact that the presence of a magnetic field significantly influences the accretion rate and its temporal variability.

Functionality Expansion of Guided Mode Radiation via On-Chip Metasurfaces.

On-chip metasurfaces play a crucial role in bridging the guided mode and free-space light, enabling full control over the wavefront of scattered free-space light in an optimally compact manner. Recently, researchers have introduced various methods and on-chip metasurfaces to engineer the radiation of guided modes, but the total functions that a single metasurface can achieve are still relatively limited. In this work, we propose a novel on-chip metasurface design that can multiplex up to four distinct functions. We can efficiently control the polarization state, phase, angular momentum, and beam profile of the radiated waves by tailoring the geometry of V-shaped nanoantennas integrated on a slab waveguide. We demonstrate several innovative on-chip metasurfaces for switchable focusing/defocusing and for multifunctional generators of orbital angular momentum beams. Our on-chip metasurface design is expected to advance modern integrated photonics, offering applications in optical data storage, optical interconnection, augmented reality, and virtual reality.

Co-evolution of dust grains and protoplanetary disks. II. Structure and evolution of protoplanetary disks: An analytical approach

Abstract In our previous study (Tsukamoto et al. 2023b, PASJ, 75, 835), we investigated the formation and early evolution of protoplanetary disks with 3D non-ideal magnetohydrodynamics simulations considering dust growth, and found that the modified equations of the conventional steady accretion disk model that consider magnetic braking, dust growth, and ambipolar diffusion reproduce the disk structure (such as density and vertical magnetic field) obtained from simulations very well. In this paper, as a sequel to our previous study, we analytically investigate the structure and evolution of protoplanetary disks corresponding to Class 0/I young stellar objects using the modified steady accretion disk model combining an analytical model of envelope accretion. We estimate that the disk radius is several astronomical units at the disk formation epoch and increases to several hundred astronomical units at the end of the accretion phase. The disk mass is estimated to be $0.01 \lesssim M_{\rm disk} \lesssim 0.1 \, M_\odot$ for a disk with a radius of several tens of astronomical units and a mass accretion rate of $\dot{M}_{\rm disk} \sim 10^{-6} \, M_\odot \,\, {\rm yr^{-1}}$. These estimates seems to be consistent with recent observations. We also found that, with typical disk ionization rates (ζ ≳ 10−19 s−1) and a moderate mass accretion rate ($\dot{M}_{\rm disk}\gtrsim 10^{-8} \, M_\odot \,\, {\rm yr^{-1}}$), magnetorotational instability is suppressed in the disk because of low plasma β and efficient ambipolar diffusion. We argue that the radial profile of specific angular momentum (or rotational velocity) at the disk outer edge should be continuously connected to that of the envelope if the disk evolves by magnetic braking, and should be discontinuous if the disk evolves by an internal angular momentum transport process such as gravitational instability or magnetorotational instability. Future detailed observations of the specific angular momentum profile around the disk outer edge are important for understanding the angular momentum transport mechanism of protoplanetary disks.

General relativistic hydrodynamic simulations of perturbed transonic accretion

Contact. Comparing horizon-scale observations of Sgr A* and M 87* with numerical simulations has provided considerable insight into their interpretation. Most of these simulations are variations of the same physical scenario consisting of a rotation-supported torus seeded with poloidal magnetic fields. However, this approach has several well-known limitations such as secular decreasing trends in mass-accretion rates that render long-term variability studies difficult; a lack of connection with the large-scale accretion flow, which is replaced by an artificial medium emulating vacuum; and significant differences with respect to the predictions of models of accretion onto Sgr A* fed by stellar winds. Aims. We aim to study the flow patterns that arise on horizon scales in more general accretion scenarios that have a clearer connection with the large-scale flow, and are at the same time controlled by a reduced set of parameters. Methods. As a first step in this direction, we performed three-dimensional general relativistic hydrodynamic simulations of rotating transonic flows with velocity perturbations injected from a spherical boundary located far away from the central object (1000 gravitational radii). We studied the general properties of these flows with varying perturbation amplitudes and angular momentum. We analyzed time series of mass and angular-momentum radial fluxes, angle- and time-averaged profiles, and synthetic bremsstrahlung light curves, as well as the three-dimensional structure of the flow, and quantified shock and sonic transitions in the solutions. Results. We observe a rich phenomenology in accretion patterns, which includes smooth Bondi-like flows, turbulent torus-like structures, shocks, filaments, and complex sonic structures. For sufficiently large perturbations and angular momentum, radial profiles deviate from the constant entropy and constant angular-momentum profiles used for initialization and resemble those of advection-dominated accretion flows, showing evidence of entropy generation and angular-momentum redistribution not mediated by magnetic fields. Time series do not show the secular decreasing trend and are suitable for long-term variability studies. We see that the fluctuations are amplified and extend further in frequency than the injected spectrum, producing a red noise spectrum both for the mass-accretion rate and the synthetic light curves. Conclusions. We present a simulation setup that can produce a wide variety of flow patterns at horizon scales and incorporate information from large scale accretion models. The future inclusion of magnetic fields and radiative cooling could make this type of simulation a viable alternative for the numerical modeling of general low-luminosity active galactic nuclei (AGNs).

Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution

Context. The fragmentation mode of high-mass molecular clumps and the accretion processes that form the most massive stars (M ≳ 8 M⊙) are still not well understood. A growing number of case studies have found massive young stellar objects (MYSOs) to harbour disk-like structures, painting a picture that the formation of high-mass stars may proceed through disk accretion, similar to that of lower-mass stars. However, the properties of such structures have yet to be uniformly and systematically characterised. Aims. The aim of this work is to uniformly study the kinematic properties of a large sample of MYSOs and characterise the stability of possible circumstellar disks against gravitational fragmentation. Methods. We have undertaken a large observational programme (CORE) making use of interferometric observations from the Northern Extended Millimetre Array (NOEMA) for a sample of 20 luminous (L &gt; 104 L⊙) protostellar objects in the 1.37 mm wavelength regime in both continuum and spectral line emission, reaching 0.4″ resolution (800 au at 2 kpc). Results. We present the gas kinematics of the full sample and detect dense gas emission surrounding 15 regions within the CORE sample. Using the dense gas tracer CH3CN, we find velocity gradients across 13 cores perpendicular to the directions of bipolar molecular outflows, making them excellent disk candidates. The extent of the CH3CN emission tracing the disk candidates varies from 1800 to 8500 au. Analysing the free-fall to rotational timescales, we find that the sources are rotationally supported. The rotation profiles of some disk candidates are well described by differential rotation while for others the profiles are poorly resolved. Fitting the velocity profiles with a Keplerian model, we find protostellar masses in the range of ~ 10–25 M⊙. Modelling the level population of CH3CN (12K–11K) K = 0–6 lines, we present temperature maps and find median temperature in the range 70–210 K with a diversity in distributions. Radial profiles of the specific angular momentum (j) for the best disk candidates span a range of 1–2 orders of magnitude, on average ~10−3 km s−1 pc, and they follow j ∝ r1.7, which is consistent with a poorly resolved rotating and infalling envelope-disk model. Studying the Toomre stability of the disk candidates, we find almost all (11 out of 13) disk candidates to be prone to fragmentation due to gravitational instabilities at the scales probed by our observations, as a result of their high disk to stellar mass ratio. In particular, disks with masses greater than ~ 10–20% of the mass of their host (proto)stars are Toomre unstable, and more luminous YSOs tend to have disks that are more massive compared to their host star and hence more prone to fragmentation. Conclusions. In this work, we show that most disk structures around high-mass YSOs are prone to disk fragmentation early in their formation due to their high disk to stellar mass ratio. This impacts the accretion evolution of high-mass protostars which will have significant implications for the formation of the most massive stars.

Generalized Terahertz Perfect Vortices with Transmutable Intensity Profiles Based on Spin‐Decoupled Geometric Metasurfaces

AbstractPerfect vortex beams (PVBs) possessing orbital angular momentum (OAM) and constant intensity profile enable practical applications in information encoding and transmission due to an unbounded number of orthogonal OAM channels and fixed annular intensity distributions. Geometric metasurfaces, which are 2D counterparts of metamaterials, have provided an ultra‐compact platform to flexibly design perfect vortex beams in a single flat device. However, the previous reported PVBs based on geometric metasurfaces are limited to ring‐shaped intensity profiles and intrinsic spin‐coupling between two orthogonal spin‐components. Here, spin‐decoupled geometric metasurfaces encoding with two‐step coordinate transformations are proposed to generate helicity‐independent PVBs with transmutable intensity profiles. By tailoring local phase gradient along the azimuthal direction, spin‐independent and polarization‐rotated terahertz (THz) PVBs with CN‐fold rotationally symmetric intensity profiles have been theoretically designed and experimentally demonstrated. Furthermore, THz PVBs with arbitrary intensity profiles have also been realized. The unique approach for simultaneously manipulating the spiral phase, focusing phase, as well as intensity profiles will open a new avenue to develop multifunctional integrated devices and systems, which enables potential applications in information processing and optical communication.

Orbital motion and quasi-periodic oscillations with periastron and Lense–Thirring precession of slowly rotating Einstein–Æther black hole

We study the orbital and oscillatory motion of test particles moving around slowly rotating first and second kinds of Einstein–Æther black holes. In relation to the black hole parameters, we find analytical solutions for the radial profiles of specific energy and specific angular momentum of the equatorial stable circular orbits. The properties of the co-rotating as well as contra-rotating innermost stable circular orbits are analyzed. We examine the radial profiles of the frequencies of latitudinal and radial harmonic oscillations as a function of the black hole mass and dimensionless coupling constants of the theory. The key features of quasi-periodic oscillations of test particles near the stable circular orbits in an equatorial plane of the black hole are discussed. We investigate the positions of resonant radii for high-frequency quasi-periodic oscillations models, namely epicyclic resonance and its variants, relativistic precession and its variants, tidal disruption, as well as warped disc models, considered in the background of slowly rotating first and second kinds of slowly rotating Einstein–Æther black holes. Furthermore, Periastron and Lense–Thirring precessions have been discussed. We demonstrate that the dimensionless coupling parameters of the theory have a strong influence on particle motion around Einstein–Æther black holes.

Evolution of the Angular Momentum of Molecular Cloud Cores Formed from Filament Fragmentation

The angular momentum of molecular cloud cores plays an important role in the process of star formation. However, the time evolution of the angular momentum of molecular cloud cores is still unclear. In this paper, we perform three-dimensional simulations to investigate the time evolution of the angular momentum of molecular cloud cores formed through filament fragmentation. As a result, we find that most of the cores rotate perpendicular to the filament axis. The mean angular momentum of the cores changes by only around 30% during the initial stage of their formation process and then remains almost constant. In addition, we analyze the internal angular momentum structure of the cores. Although the cores gain angular momentum with various directions from the initial turbulent velocity fluctuations of their parent filaments, the angular momentum profile in each core converges to the self-similar solution. We also show that the degree of complexity of the angular momentum structure in a core decreases slightly with time. Moreover, we perform synthetic observations and show that the angular momentum profile measured from the synthetic mean velocity map is compatible with the observations when the filament inclination is taken into account. The present study suggests a theory of core formation from filament fragmentation where the angular momentum structures of the cores are determined by the velocity fluctuation along the filaments and both are compatible with the observations. This theory also provides new insights into the core properties that could be tested observationally.

Capturing the amplitude and phase profile of the vortex beam based on coherent detection

In this study, we propose a scheme to capture the amplitude and phase profile of the orbital angular momentum (OAM) beam based on coherent detection. In the scheme, the OAM beam to be measured is interfered with a local plain wave which is prepared at the receiver, and two charge-coupled devices (CCDs) are used to record the constructive and destructive interference patterns. By setting the phase of the plain wave to π/2 and π, one can extract the amplitude and phase profile of the OAM beam from the two interference patterns. We verify the feasibility of the scheme by simulation and experiments. The results show that both amplitude and phase profiles of single OAM and OAM superposition modes can be captured by using the proposed scheme, and the proposed scheme shows strong robustness even under the presence of atmospheric turbulence.

Which Part of Dense Cores Feeds Material to Protostars? The Case of L1489 IRS

Abstract We have conducted mapping observations (∼2′ × 2′) of the Class I protostar L1489 IRS using the 7 m array of the Atacama Compact Array and the IRAM 30 m telescope in C18O 2–1 emission to investigate the gas kinematics on 1000–10,000 au scales. The C18O emission shows a velocity gradient across the protostar in a direction almost perpendicular to the outflow. The radial profile of the peak velocity was measured from a C18O position–velocity diagram cut along the disk major axis. The measured peak velocity decreases with radius at radii of ∼1400–2900 au, but increases slightly or is almost constant at radii of r ≳ 2900 au. Disk-and-envelope models were compared with the observations to understand the nature of the radial profile of the peak velocity. The measured peak velocities are best explained by a model where the specific angular momentum is constant within a radius of 2900 au but increases with radius outside 2900 au. We calculated the radial profile of the specific angular momentum from the measured peak velocities and compared it to analytic models of core collapse. The analytic models reproduce well the observed radial profile of the specific angular momentum and suggest that material within a radius of ∼4000–6000 au in the initial dense core has accreted to the central protostar. Because dense cores are typically ∼10,000–20,000 au in radius, and as L1489 IRS is close to the end of its mass accretion phase, our result suggests that only a fraction of a dense core eventually forms a star.

The Three-dimensional Collapse of a Rapidly Rotating 16 M ⊙ Star

Abstract I report on the three-dimensional (3D) hydrodynamic evolution of a rapidly rotating 16 M ⊙ star to iron core collapse. For the first time, I follow the 3D evolution of the angular momentum (AM) distribution in the iron core and convective shell burning regions for the final 10 minutes up to and including gravitational instability and core collapse. In 3D, convective regions show efficient AM transport that leads to an AM profile that differs in shape and magnitude from MESA within a few shell convective turnover timescales. For different progenitor models, such as those with tightly coupled Si/O convective shells, efficient AM transport in 3D simulations could lead to a significantly different AM distribution in the stellar interior affecting estimates of the natal neutron star or black hole spin. The results suggest that 3D AM transport in convective and rotating shell burning regions are critical components in models of massive stars and could qualitatively alter the explosion outcome and inferred compact remnant properties.

VLA and NOEMA Views of Bok Globule CB 17: The Starless Nature of a Proposed First Hydrostatic Core Candidate

Abstract We use 3 mm continuum NOrthern Extended Millimeter Array and NH3 Very Large Array observations toward the First Hydrostatic Core (FHSC) candidate CB 17 MMS in order to reveal the dust structure and gas properties to 600–1100 au scales and to constrain its evolutionary stage. We do not detect any compact source at the previously identified 1.3 mm point source, despite expecting a minimum signal-to-noise ratio of 9. The gas traced by NH3 exhibits subsonic motions, with an average temperature of 10.4 K. A fit of the radial column density profile derived from the ammonia emission finds a flat inner region of radius ∼1800 au and a central density of ∼6 × 105 cm−3. Virial and density structure analysis reveals the core is marginally bound (α vir = 0.73). The region is entirely consistent with that of a young starless core, hence ruling out CB 17 MMS as an FHSC candidate. Additionally, the core exhibits a velocity gradient aligned with the major axis, showing an arc-like structure in the position–velocity diagram and an off-center region with high velocity dispersion, caused by two distinct velocity peaks. These features could be due to interactions with the nearby outflow, which appears to deflect due to the dense gas near the NH3 column density peak. We investigate the specific angular momentum profile of the starless core, finding that it aligns closely with previous studies of similar radial profiles in Class 0 sources. This similarity to more evolved objects suggests that motions at 1000 au scales are determined by large-scale dense cloud motions, and may be preserved throughout the early stages of star formation.

Computational Behavior of Second Law Poiseuille Flow of Micropolar Fluids in a Channel: Analytical Treatment

The present analysis explores an analytical treatment for the computation of Poiseuille flow of a micropolar fluid in a channel placed in between two horizontal parallel plates. Both the plates are placed at constant wall temperatures. Therefore, the flow region is portioned into two different zones named zone I and zone II. Eringen’s micropolar fluid flow phenomena are taking place assuming no-slip conditions at the interface. Suitable nondimensional variables are imposed for the transformation of governing equations. Analytical treatment is carried out employing the in-house symbolic command using the MAPLE software. The behavior of several contributing parameters such as material parameters, the couple stresses for both the zones on the velocity, and microrotation profiles are investigated and presented via graphs. The volume flow rate is also calculated and presented via the tabular form. The major outcomes of the results are presented as the higher the Reynolds number, the rate increases significantly. The profile is tiled near the central region with a pick starting from the lower plate region to the central region in zone I and retards from the central region to the upper plate in the zone II, and the profiles of angular momentum seem to be symmetric in nature about the central region that is shown in both the zones.

Thermo-mechanical Transport in Rotor Chains

We study the macroscopic profiles of temperature and angular momentum in the stationary state of chains of rotors under a thermo-mechanical forcing applied at the boundaries. These profiles are solutions of a system of diffusive partial differential equations with boundary conditions determined by the thermo-mechanical forcing. Instead of expensive Monte Carlo simulations of the underlying microscopic dynamics, we perform extensive numerical computations based on a finite difference method for the system of partial differential equations describing the macroscopic steady state. We first present a formal derivation of these stationary equations based on a linear response argument and local equilibrium assumptions. We then study various properties of the solutions to these equations. This allows to characterize the regime of parameters leading to uphill energy diffusion -- a situation in which the energy flows in the direction of the gradient of temperature -- and to identify regions of parameters corresponding to a negative energy conductivity (i.e. a positive linear response of the energy current to a gradient of temperature). The macroscopic equations we derive are consistent with some previous results obtained by numerical simulation of the microscopic physical system, which confirms their validity.

Rotating Filament in Orion B: Do Cores Inherit Their Angular Momentum from Their Parent Filament?

Abstract Angular momentum is one of the most important physical quantities that governs star formation. The initial angular momentum of a core may be responsible for its fragmentation, and can have an influence on the size of the protoplanetary disk. To understand how cores obtain their initial angular momentum, it is important to study the angular momentum of filaments where they form. While theoretical studies on filament rotation have been explored, there exist very few observational measurements of the specific angular momentum in star-forming filaments. We present high-resolution N2D+ ALMA observations of the LBS 23 (HH24-HH26) region in Orion B, which provide one of the most reliable measurements of the specific angular momentum in a star-forming filament. We find the total specific angular momentum (4 × 1020 cm2 s−1), the dependence of the specific angular momentum with radius (j(r) ∝ r 1.83), and the ratio of rotational energy to gravitational energy (β rot ∼ 0.04) comparable to those observed in rotating cores with sizes similar to our filament width (∼0.04 pc) in other star-forming regions. Our filament angular momentum profile is consistent with rotation acquired from ambient turbulence and with simulations that show cores and their host filaments develop simultaneously due to multi-scale growth of nonlinear perturbation generated by turbulence.

Propagation of structured light through tissue-mimicking phantoms.

Optical interrogation of tissues is broadly considered in biomedical applications. Nevertheless, light scattering by tissue limits the resolution and accuracy achieved when investigating sub-surface tissue features. Light carrying optical angular momentum or complex polarization profiles, offers different propagation characteristics through scattering media compared to light with unstructured beam profiles. Here we discuss the behaviour of structured light scattered by tissue-mimicking phantoms. We study the spatial and the polarization profile of the scattered modes as a function of a range of optical parameters of the phantoms, with varying scattering and absorption coefficients and of different lengths. These results show the non-trivial trade-off between the advantages of structured light profiles and mode broadening, stimulating further investigations in this direction.

On the accretion of a new group of galaxies on to Virgo: I. Internal kinematics of nine in-falling dEs

ABSTRACT Galaxy environment has been shown to play an important role in transforming late-type, star-forming galaxies to quiescent spheroids. This transformation is expected to be more severe for low-mass galaxies ($M \lt 10^{10}\, \mathrm{M}_\odot$) in dense galaxy groups and clusters, mostly due to the influence of their past host haloes (also known as pre-processing) and their present-day environments. For the first time, in this study, we investigate a sample of nine early-type dwarf galaxies (dEs) that were accreted as a likely bound group on to the Virgo galaxy cluster about 2–3 Gyr ago. Considering this special condition, these nine dEs may provide a test bed for distinguishing between the influence of the Virgo galaxy cluster and the effects of the previous host halo on their current properties. Specifically, we use VLT/MUSE integral-field unit spectra to derive their kinematics and specific angular momentum (λR) profiles. We observe a spread in the λR profiles of our sample dEs, finding that the λR profiles of half of them are as high as those of low-mass field galaxies. The remaining dEs exhibit λR profiles as low as those of Virgo dEs that were likely accreted longer ago. Moreover, we detect nebular emission in one dE with a gas velocity offset suggesting ongoing gas stripping in Virgo. We suggest that the low-λR dEs in our sample were processed by their previous host halo, prior to their infall to Virgo, and that the high-λR dEs may be experiencing ram pressure stripping in Virgo.