Shallow Potential Wells Research Articles

One-sided H α excess before the first pericentre passage in galaxy pairs

ABSTRACT We present novel insights into the interplay between tidal forces and star formation in interacting galaxies before their first pericentre passage. We investigate seven close pair galaxies devoid of visible tidal disturbances, such as tails, bridges, and shells. Using integral field spectroscopy data of extended Calar Alto Legacy Integral Field Area, we unveil a previously unreported phenomenon: H $\alpha$ emission, a proxy for recent star formation, exhibits a significant enhancement in regions facing the companion galaxy, reaching up to 1.9 times higher flux compared to opposite directions. Notably, fainter companions within pairs display a more pronounced one-sided H $\alpha$ excess, exceeding the typical range observed in isolated galaxies with 2$\sigma$ confidence level. Furthermore, the observed H $\alpha$ excess in fainter companion galaxies exhibits a heightened prominence at the outer galactic regions. These findings suggest that tidal forces generated before the first pericentre passage exert a stronger influence on fainter galaxies due to their shallower potential wells by their brighter companions. This unveils a more intricate interplay between gravitational interactions and star formation history within interacting galaxies than previously understood, highlighting the need further to explore the early stages of interaction in galaxy evolution.

Quantum State-Resolved Nonadiabatic Dynamics of the H+NaF → Na+HF Reaction

The H + NaF reaction is investigated at the quantum state-resolved level using the time-dependent wave-packet method based on a set of accurate diabatic potential energy surfaces. Oscillatory structures in the total reaction probability indicate the presence of the short-lived intermediate complex, attributed to a shallow potential well and exothermicity. Ro-vibrational state-resolved integral cross sections reveal the inverted population distributions of the product. The HF product favors an angular distribution in the forward hemisphere of 30°–60° within the collision energy range from the threshold to 0.50 eV, which is related to the nonlinear approach of the H atom to the NaF molecule. Quantum generalized deflection functions show that the low-J partial waves contribute primarily to the backward scattering, while the high-J partial waves govern the forward scattering. The correlation between the partial wave J and the scattering angle ϑ proves that the reaction follows a predominant direct reaction mechanism.

A Census of Star Formation Histories of Massive Galaxies at 0.6 < z < 1 from Spectrophotometric Modeling Using Bagpipes and Prospector

We present individual star formation histories (SFHs) of ∼3000 massive galaxies (log(M */M ⊙) > 10.5) from the Large Early Galaxy Astrophysics Census spectroscopic survey at a lookback time of ∼7 billion yr and quantify the population trends leveraging 20 hr deep-integrated spectra of these ∼1800 star-forming and ∼1200 quiescent galaxies at 0.6 < z < 1.0. Essentially all galaxies at this epoch contain stars of age <3 Gyr, in contrast with older massive galaxies today, facilitating better recovery of previous generations of star formation at cosmic noon and earlier. We conduct spectrophotometric analysis using parametric and nonparametric Bayesian stellar population synthesis modeling tools—Bagpipes and Prospector—to constrain the median SFHs of this mass complete sample and characterize population trends. A consistent picture arises for the late-time stellar mass growth when quantified as t 50 and t 90, corresponding to the age of the Universe when galaxies formed 50% and 90% of their total stellar mass, although the two methods disagree at the earliest formation times (e.g., t 10). Our results reveal trends in both stellar mass and stellar velocity dispersion as in the local Universe—low-mass galaxies with shallower potential wells grow their stellar masses later in cosmic history compared to high-mass galaxies. Unlike local quiescent galaxies, the median duration of late-time star formation (τ SF,late = t 90–t 50) does not consistently depend on the stellar mass. This census sets a benchmark for future deep spectrophotometric studies of the more distant Universe.

Boosting output performance of tri-hybrid vibration-based generator via quin-stable nonlinearity and speed amplification

A high-performance tri-hybrid vibration-driven generator with quin-stability and speed amplification characteristics is presented. This design integrates three different mechanisms in a compact and interactive working mode to enhance power density. Exploiting the quin-stable nonlinear behavior to the dynamic system creates a shallow potential well that can be triggered under broadband, low-level, and random ambient sources. In addition, the implementation of the rack and pinion steering system not only doubles the relative motion of the translators’ moving components in the electromagnetic and triboelectric units, and also increases the number of operations per cycle of the frequency up-conversion piezoelectric units. Consequently, the output performance of this tri-hybrid generator is significantly enhanced. To examine the working efficiency of this design, an experimental model is assembled and tested. In the shaker test, the peak output power of the prototype can be boosted to ∼822 mW, and the maximum power density is 7.74 mW cm−3 g−2 subjected to low excitation levels (5 Hz and 1-g acceleration). Experimental demonstrations are also carried out to exhibit the exceptional performance of this design that can support various power levels of electronic devices under human-induced motions.

Unidirectional flow of flat-top solitons

We numerically demonstrate the unidirectional flow of flat-top solitons when interacting with two reflectionless potential wells with slightly different depths. The system is described by a nonlinear Schrödinger equation with dual nonlinearity. The results show that for shallow potential wells, the velocity window for unidirectional flow is larger than for deeper potential wells. A wider flat-top solitons also have a narrow velocity window for unidirectional flow than those for thinner flat-top solitons.

Tunneling Mechanism for Changing the Motion Direction of a Pulsating Ratchet. Temperature Effect

A pulsating ratchet with a spatially periodic double-well potential profile undergoing shift fluctuations for half a period is considered. The motion direction in such a ratchet is determined by the probability of overcoming which of the barriers surrounding the shallow potential well is greater. At relatively high temperatures, in accordance with the Arrhenius law, the probabilities of overcoming the barriers are determined by their heights, and at temperatures close to absolute zero, when the ratchet moves according to the tunnel mechanism, the barrier shapes are also important. Therefore, for narrow high and low wide barriers, the overcoming mechanism may turn out to be different and, moreover, dependent on temperature. As a result, a temperature-induced change in the direction of the ratchet motion is possible. A simple interpolation theory is presented to illustrate this effect. Simple criteria are formulated for the shape of the potential relief, using which one can experimentally observe motion reversal.

Design and performance evaluation of novel magnetic tristable wave energy converter

To realize efficient broadband wave-energy conversion, this study proposes a point-absorber wave energy converter with a novel magnetic tristable mechanism (NMT-PAWEC). The tristable mechanism consists of coaxial inner and outer magnetic rings. The outer magnetic ring features two types of sector magnets with opposite poles. The motion control equations of the NMT-PAWEC are established using the Cummins equation and the equivalent magnetic charge method. The preferred parameter region of the novel tristable mechanism was investigated, and the energy-conversion performance of the NMT-PAWEC under regular waves was analyzed. The results show that the NMT-PAWEC with shallower potential wells can easily achieve inter-well oscillation under low-amplitude waves, with higher energy harvesting efficiency, and a wider frequency and work-damping band. Through a nonlinear bifurcation dynamics analysis, the causes of fluctuations and sudden changes in the output power under low-amplitude waves were revealed. Furthermore, the capture width ratio and annual average power of the South China Sea were considered. The influence of optimized PTO parameters on the energy-conversion performance of the NMT-PAWEC in regular and irregular waves was further discussed. In general, the efficient broadband power output capabilities demonstrate the excellent applicability of NMT-PAWEC.

A possible signature of the influence of tidal perturbations in dwarf galaxy scaling relations

ABSTRACT Dwarf galaxies are excellent cosmological probes, because their shallow potential wells make them very sensitive to the key processes that drive galaxy evolution, including baryonic feedback, tidal interactions, and ram pressure stripping. However, some of the key parameters of dwarf galaxies, which help trace the effects of these processes, are still debated, including the relationship between their sizes and masses. We re-examine the Fornax Cluster dwarf population from the point of view of isomass-radius–stellar mass relations (IRSMRs) using the Fornax Deep Survey Dwarf galaxy Catalogue, with the centrally located (among dwarfs) $3.63 \mathcal {M}_{\odot }$ pc−2 isodensity radius defining our fiducial relation. This relation is a powerful diagnostic tool for identifying dwarfs with unusual structure, as dwarf galaxies’ remarkable monotonicity in light profile shapes, as a function of stellar mass, reduces the relation’s scatter tremendously. By examining how different dwarf properties (colour, 10th nearest neighbour distance, etc.) correlate with distance from our fiducial relation, we find a significant population of structural outliers with comparatively lower central mass surface density and larger half-light-radii, residing in locally denser regions in the cluster, albeit with similar red colours. We propose that these faint, extended outliers likely formed through tidal disturbances, which make the dwarfs more diffuse, but with little mass-loss. Comparing these outliers with ultra-diffuse galaxies (UDGs), we find that the term UDG lacks discriminatory power; UDGs in the Fornax Cluster lie both on and off of IRSMRs defined at small radii, while IRSMR outliers with masses below $\sim 10^{7.5} \mathcal {M}_{\odot }$ are excluded from the UDG classification due to their small effective radii.

Anomalous hydrogen diffusion in VCr alloys: Trapping hydrogen via shallow potential well domains

In this paper, the dynamic of hydrogen diffusion in the VCr alloy is investigated by the first-principles calculations and kinetic Monte Carlo method. First, the structural stability as a function of components is explored, where the stable configurations hold high symmetry. For the stable structures, the hydrogen diffusivity is found to decrease first and then increase as the Cr content increases. The hydrogen diffusivity is calculated to be the slowest in V0.375Cr0.625, a structure with the space group P4/mmm. The results show that the main factor affecting the diffusion is not only the magnitude of a single barrier, but the overall spatial distribution of barriers, correspondent to the distribution of Cr atoms in VCr alloy. Furthermore, an unbalanced one-dimensional random walk model is proposed to well describe the phenomenon of anomalous hydrogen diffusion and elucidate the mechanism of hydrogen migration in the alloy.

Design and numerical investigation of an ultra-wide bandwidth rolling magnet bistable electromagnetic harvester

To realize broadband energy harvesting at low-frequency excitation, this paper proposes a rolling magnet bistable electromagnetic harvester (RM-BEH) which utilizes the rolling motion of a magnetically levitated magnet. The dynamic model of the RM-BEH is established, based on which the output of the RM-BEH is predicted through electromagnetic induction combined with finite element analysis. By calculating the parameter region for monostable and bistable configurations, the broadband response characteristics of a bistable system with shallower potential wells are investigated. Results show that the RM-BEH could achieve interwell oscillation in the frequency range between 5.8 Hz and 22 Hz under sweep frequency excitation with a level of 0.5 g. Under constant frequency excitation, multiple vibrational patterns of the RM-BEH are presented and examined. To identify the multiple solutions, harmonic balance method results are presented, indicating that high-energy orbit oscillation can be achieved with appropriate initial conditions. Furthermore, the response of RM-BEH under Gaussian white noise and human motion excitations is considered and results indicate that the RM-BEH could travel across the potential wells easily to generate large output. In general, the broadband response characteristic under harmonic excitation and considerable output under human motion excitation demonstrate the excellent application foreground of the RM-BEH.

High-Level Theoretical Study of the C1Π States of GaCl, GaBr, InCl, and InBr.

For the first singlet excited states C1Π of IIIA group monohalides GaCl, GaBr, InCl, and InBr, a very shallow potential well may exist in the flat potential energy curve, which poses a challenge to the theoretical accuracy. In this study, high-level theoretical calculations have been performed through the Feller-Peterson-Dixon composite approach to study the C1Π states, and the obtained spectroscopic constants agree well with the known experimental ones. It is found that the C1Π states are sensitive to the size of basis functions, spin-orbit coupling, and strong correlations mainly due to triple excitations. The final results show that the C1Π states of GaCl and InCl are quasi-bound with one (v' = 0) and four (v' = 0-3) vibrational levels, respectively, being consistent with the experimental findings, whereas the C1Π states of GaBr and InBr are repulsive. Our conclusions deny the existence of higher vibrational levels v' = 1 for GaCl, v' > 3 for InCl, and v' ≥ 0 for InBr in previous experimental and theoretical studies of C1Π.

On a spring-assisted multi-stable hybrid-integrated vibration energy harvester for ultra-low-frequency excitations

This work presents a spring-assisted multi-stable nonlinear vibration energy harvesting technique by integrating two working mechanisms (i.e., electromagnetic and triboelectric generators) into an interactive manner. To overcome the technical barrier of vibration energy harvesters with poor environmental adaptability, this hybrid design approach enables to harness more vibration energy under random and low-level excitation levels. In addition, we further incorporate a metallic spring-based multi-stable dynamical system that can simplify the mechanical design for working well in real-engineering conditions. Implementing the strategy of multi-stable nonlinear behavior, shallower potential wells of the dynamical system can be achieved by adjusting (i) the interaction between the outer fixed magnets and the inner moving magnet; and (ii) the inner moving magnet and its separation with the springs. This flexible arrangement is able to enhance the working performance under an ultra-low excitation threshold (1–5 Hz). By a parametric study, the influence of geometric parameters on the proposed system is analyzed. The experimental results indicate that the present device can produce a peak power of 165.3 mW under 5 Hz and 1 g, implying the estimated peak power density of about 2261.3 W/m3. The new design proposed here offers another perspective on the mechanical design and dynamical characteristics for efficient vibration energy harvesting.

Probing the Disorder Inside the Cubic Unit Cell of Halide Perovskites from First-Principles.

Strong deviations in the finite temperature atomic structure of halide perovskites from their average geometry can have profound impacts on optoelectronic and other device-relevant properties. Detailed mechanistic understandings of these structural fluctuations and their consequences remain, however, limited by the experimental and theoretical challenges involved in characterizing strongly anharmonic vibrational characteristics and their impact on other properties. We overcome some of these challenges by a theoretical characterization of the vibrational interactions that occur among the atoms in the prototypical cubic CsPbBr3. Our investigation based on first-principles molecular dynamics calculations finds that the motions of neighboring Cs-Br atoms interlock, which appears as the most likely Cs-Br distance being significantly shorter than what is inferred from an ideal cubic structure. This form of dynamic Cs-Br coupling coincides with very shallow dynamic potential wells for Br motions that occur across a locally and dynamically disordered energy landscape. We reveal an interesting dynamic coupling mechanism among the atoms within the nominal unit cell of cubic CsPbBr3 and quantify the important local structural fluctuations on an atomic scale.

Nonadiabatic decay of Rydberg-atom–ion molecules

The decay of Rydberg-atom-ion molecules (RAIMs) due to non-adiabatic couplings between electronic potential energy surfaces is investigated. We employ the Born-Huang representation and perform numerical simulations using a Crank-Nicolson algorithm. The non-adiabatic lifetimes of rubidium RAIMs for the lowest ten vibrational states, $\nu$, are computed for selected Rydberg principal quantum numbers, $n$. The non-adiabatic lifetimes are found to generally exceed the radiative Rydberg-atom lifetimes. We observe and explain a trend of the lifetimes as a function of $\nu$ and $n$, and attribute irregularities to quantum interference arising from a shallow potential well in an inner potential surface. Our results will be useful for future spectroscopic studies of RAIMs.

Stationary structures of spin-orbit coupled polariton condensates in Bessel lattices

&lt;sec&gt;Bessel optical lattice yields a non-spatially periodic column-symmetric optical lattice potential field, which has the characteristics of both infinite deep potential well and the ring-shaped potential well. A deep potential is formed in the center of the 0-order Bessel optical lattice. In the non-zero-order Beseel optical lattice, a ring-shaped shallow potential well with a central barrier can be formed. Exciton-polariton is a semi-light and semi-matter quasi-particle, which can achieve the Bose-Einstein condensate phase transition even at room temperature to form a polariton condensate. In addition, the polariton condensate is likely to realize sufficiently strong spin-orbit coupling due to the cavity-induced TE-TM splitting of the polariton energy levels. The polariton condensate can be realized at room temperature, and there can be spin-orbit coupling in it, which provides a new platform for the studying of quantum physics. &lt;/sec&gt;&lt;sec&gt;In this paper, the Bessel optical lattice is introduced into a polariton condensate. The stationary state structure of spinor two-component polariton condensate with spin-orbit coupling is investigated. By solving the Gross-Pitaevskii equation, we first give a stationary state structures of the polariton condensate both in the laboratory coordinate frame and in the rotating coordinate frame. Owing to the introduction of the Bessel optical lattice, the stationary state structures of polariton condensate are diverse. We dispaly the stationary state structures of the basic Gaussian solitons and multipole solitons in the central deep potential well in the laboratory coordinate frame, and the ring solitons and multipole solitons in the central shallow potential well. We also dispaly the vortex ring soliton that exists in the rotating coordinate frame, and the stationary state structure of the component separation caused by the spin-orbit interaction. We analyze not only the influences of the spin-orbit coupling on the stationary state structures in the two coordinate frames, but also the stability of the multipole solitons in the rotating coordinate frame. It is found that the multipole solitons formed in the ring-shaped shallow potential well have better stability than in the central deep potential well, and they can maintain the relative structure and spatial distribution for a long time in the rotation process. In the rotating coordinate frame, even if the two-component separation conditions are not satisfied, the introduction of spin-orbit coupling can cause the two components to separate.&lt;/sec&gt;

Equilibrium Charge Distribution in a Finite Chain with a Trapping Site

The paper considers the problem of the distribution of a quantum particle in a classical one-dimensional lattice with a potential well. The cases of a rigid chain, a Holstein polaron model, and a polaron in a chain with temperature are investigated by direct modeling at fixed parameters. As is known, in the one-dimensional case, a particle is captured by an arbitrarily shallow potential well with an increase of the box size. In the case of a finite chain and finite temperatures, we have quite the opposite result, when a particle, being captured in a well in a short chain, turns into delocalized state with an increase in the chain length. These results may be helpful for further understanding of charge transfer in DNA, where oxoguanine can be considered as a potential well in the case of hole transfer when for excess electron transfer it is thymine dimer.

Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ &amp;lt; 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

Observation of Cesium (nD 5/2+6S 1/2) Ultralong-Range Rydberg-Ground MoleculesSupported by the National Key R&D Program of China (Grant No. 2017YFA0304203), the National Natural Science Foundation of China (Grant Nos. 11434007, 61835007, 61675123, 61775124, and 11904215), Changjiang Scholars and Innovative Research Team in Universities of Ministry of Education of China (Grant No. IRT 17R70), and the 1331 Project.

Ultralong-range Cs2 Rydberg-ground molecules (nD 5/2 + 6S 1/2 F) (33 ≤ n ≤ 39, F = 3 or 4) are investigated by a two-photon photo-association spectroscopy of an ultracold Cs gas. Two vibrational ground molecular spectra of triplet 3 Σ and hyperfine mixed singlet-triplet 1,3 Σ molecular states and their corresponding binding energies are attained. The experimental observations are simulated by an effective Hamiltonian including low energy electron scattering pseudopotentials, the spin-orbit interaction of the Rydberg atom, and the hyperfine interaction of the ground-state atom. The zero-energy singlet and triplet s-wave scattering lengths are extracted by comparing the experimental observations and calculations. Dependences of the measured binding energies on the effective principal quantum number, n eff = n − δD (δD is the quantum defect of Rydberg D state), yield the scaling of , for deep triplet potential and , for shallow mixed singlet-triplet potential well. The simulations of low-energy Rydberg electron scattering show agreement well with the experimental measurements.

Elucidation of the Underlying Mechanism of CO2 Capture by Ethylenediamine-Functionalized M2(dobpdc) (M = Mg, Sc-Zn).

We, for the first time, systematically investigated the crystal structures, adsorption properties, and microscopic mechanism of CO2 capture with ethylenediamine (en)-appended isostructural M2(dobpdc) materials (M = Mg, Sc-Zn), using spin polarized density functional theory (DFT) calculations. The binding energies of en range from 142 to 210 kJ/mol. The weakest binding materials are en-Cr2(dobpdc) and en-Cu2(dobpdc). Two typical models, the pair model and the chain model, have been considered for CO2 adsorption. Generally, the chain model is more stable than the pair model. The CO2 adsorption energies of the chain model are in the range of 30-96 kJ/mol, with a strong metal dependence. Among these, the en-Sc2(dobpdc) and en-Cu2(dobpdc) have the highest and lowest CO2 adsorption energies, respectively. Moreover, the dynamic progress of CO2 adsorption has been unveiled via exploration of the full reaction pathway, including transition states and intermediates. First, the CO2 molecule interacts with en-MOFs to form a physisorbed complex with a shallow potential well. This is followed by overcoming a relatively large energy barrier to form a chemisorbed complex. Finally, ammonium carbamate is formed along the one-dimensional channels within the pore with a small energy barrier for configuration transformation. These results agree well with the experimental observations. Understanding the detailed microscopic mechanism of CO2 capture is quite crucial for improving our fundamental knowledge base and potential future applications. This work will improve our understanding of CO2 adsorption with amine functionalized MOFs. We expect our results to stimulate future experimental and theoretical research and advance the development of this field.

RESONANCE AS NEW METHOD IN DETERMINING THE AGE OF PAINTS

In this work the mechanism of resonance is proposed as the way for determining of paint age, by application of this method. This method consists in accelerated paint ageing on the basis of resonance. Measuring is concerned with humidity of paint and it is a general method since water molecules are present in every material. The molecules of water have random distribution. They oscillate in shallow potential wells so that they can be ejected from paint with low energy quanta, thus decreasing the paint humidity by evaporation process. The high energy quanta accelerate this process of the paint ageing. Since water molecule is mechanical oscillator it can be turned into resonance by application of mechanical periodical field, but since it is electric dipole it can be even more conveniently turned into resonance with periodic electric field.