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2021-06-10
Constraining extra dimensions using observations of black hole quasi-normal modes
The presence of extra dimensions generically modify the spacetime geometry of a rotating black hole, by adding an additional hair, besides the mass $M$ and the angular momentum $J$, known as the `tidal charge' parameter, $\beta$. In a braneworld scenario with one extra spatial dimension, the extra dimension is expected...
2106.05558v2
2021-06-24
A Polarizable Water Potential Derived from a Model Electron Density
A new empirical potential for efficient, large scale molecular dynamics simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular Polarizable POtential) force field is based upon the model electron density of a hydrogen-like atom. This framework is used to derive and parameterize individual terms descri...
2106.13116v3
2021-07-19
Long term behavior of 2D and 3D non-autonomous random convective Brinkman-Forchheimer equations driven by colored noise
The long time behavior of Wong-Zakai approximations of 2D as well as 3D non-autonomous stochastic convective Brinkman-Forchheimer (CBF) equations with non-linear diffusion terms on bounded and unbounded ($\mathbb{R}^d$ for $d=2,3$) domains is discussed in this work. To establish the existence of random pullback attract...
2107.08890v1
2021-07-28
Queue-Channel Capacities with Generalized Amplitude Damping
The generalized amplitude damping channel (GADC) is considered an important model for quantum communications, especially over optical networks. We make two salient contributions in this paper apropos of this channel. First, we consider a symmetric GAD channel characterized by the parameter $n=1/2,$ and derive its exact...
2107.13486v1
2021-07-31
Damped inertial dynamics with vanishing Tikhonov regularization: strong asymptotic convergence towards the minimum norm solution
In a Hilbert space, we provide a fast dynamic approach to the hierarchical minimization problem which consists in finding the minimum norm solution of a convex minimization problem. For this, we study the convergence properties of the trajectories generated by a damped inertial dynamic with Tikhonov regularization. Whe...
2108.00203v1
2021-08-13
Nonlinear modal testing of damped structures: Velocity feedback vs. phase resonance
In recent years, a new method for experimental nonlinear modal analysis has been developed, which is based on the extended periodic motion concept. The method is well suited to experimentally obtain amplitude-dependent modal properties (modal frequency, damping ratio and deflection shape) for strongly nonlinear systems...
2108.06189v1
2021-09-21
Double diffusion structure of logarithmically damped wave equations with a small parameter
We consider a wave equation with a nonlocal logarithmic damping depending on a small parameter $\theta \in (0,1/2)$. This research is a counter part of that was initiated by Charao-D'Abbicco-Ikehata considered in [5] for the large parameter case $\theta \in (1/2,1)$. We study the Cauchy problem for this model in the wh...
2109.09944v2
2021-09-21
Non-intrusive Balancing Transformation of Highly Stiff Systems with Lightly-damped Impulse Response
Balanced truncation (BT) is a model reduction method that utilizes a coordinate transformation to retain eigen-directions that are highly observable and reachable. To address realizability and scalability of BT applied to highly stiff and lightly-damped systems, a non-intrusive data-driven method is developed for balan...
2109.10408v2
2021-10-08
Site characterization at Treasure Island and Delaney Park downhole arrays by heterogeneous data assimilation
This article extends a recently proposed heterogeneous data assimilation technique for site characterization to estimate compression and shear wave velocity (Vp and Vs, respectively) and damping at Treasure Island and Delaney Park downhole arrays. The adopted method is based on the joint inversion of earthquake acceler...
2110.03849v1
2021-11-01
On the stochastic nature of Galactic cosmic-ray sources
The precision measurements of the spectra of cosmic ray nuclei and leptons in recent years have revealed the existence of multiple features, such as the spectral break at $\sim 300$ GV rigidity seen by PAMELA and AMS-02 and more recently confirmed by DAMPE and CALET, the softening in the spectra of H and He nuclei at $...
2111.01171v2
2021-11-09
The In Situ Signature of Cyclotron Resonant Heating
The dissipation of magnetized turbulence is an important paradigm for describing heating and energy transfer in astrophysical environments such as the solar corona and wind; however, the specific collisionless processes behind dissipation and heating remain relatively unconstrained by measurements. Remote sensing obser...
2111.05400v2
2021-11-10
Quantum amplitude damping for solving homogeneous linear differential equations: A noninterferometric algorithm
In contexts where relevant problems can easily attain configuration spaces of enormous sizes, solving Linear Differential Equations (LDEs) can become a hard achievement for classical computers; on the other hand, the rise of quantum hardware can conceptually enable such high-dimensional problems to be solved with a for...
2111.05646v2
2021-11-13
Attenuation of surface modes in granular media
In this work, an unconsolidated granular medium, made of silica microbeads, is experimentally tested in a laboratory setting. The objective is to investigate the attenuation mechanisms of vertically polarized seismic waves traveling at the surface of unconsolidated substrates that are characterized by power-law rigidit...
2111.07199v1
2021-11-15
The Interplay of Regularizing Factors in the Model of Upper Hybrid Oscillations of Cold Plasma
A one-dimensional nonlinear model of the so-called upper hybrid oscillations in a magnetoactive plasma is investigated taking into account electron-ion collisions. It is known that both the presence of an external magnetic field of strength $ B_0 $ and a sufficiently large collisional factor $ \nu $ help suppress the f...
2111.07826v3
2021-11-20
Excitation and Damping of Slow Magnetosonic Waves in Flaring Hot Coronal Loops: Effects of Compressive Viscosity
Slow magnetosonic waves associated with flares were observed in coronal loops by SOHO/SUMER, SDO/AIA in various EUV bandpasses, and other instruments. The excitation and damping of slow magnetosonic waves provides information on the magnetic, temperature, and density structure of the loops. Recently, it was found using...
2111.10696v1
2021-12-22
Strong Stabilization of a 3D Potential Flow via a Weakly Damped von Karman Plate
The elimination of aeroelastic instability (resulting in sustained oscillations of bridges, buildings, airfoils) is a central engineering and design issue. Mathematically, this translates to strong asymptotic stabilization of a 3D flow by a 2D elastic structure. The stabilization (convergence to the stationary set) of ...
2112.12208v1
2021-12-28
Kinetic investigation of the planar Multipole Resonance Probe under arbitrary pressure
Active plasma resonance spectroscopy (APRS) refers to a class of plasma diagnostic methods that use the ability of plasma to resonate at or near the electron plasma frequency for diagnostic purposes. The planar multipole resonance probe (pMRP) is an optimized realization of APRS. It has a non-invasive structure and all...
2112.14190v2
2021-12-28
Metadamping in inertially amplified metamaterials: Trade-off between spatial attenuation and temporal attenuation
Metadamping is the phenomenon of either enhanced or diminished intrinsic dissipation in a material stemming from the material's internal structural dynamics. It has been previously shown that a locally resonant elastic metamaterial may be designed to exhibit higher or lower dissipation compared to a statically equivale...
2112.14322v1
2022-01-10
Tidal erasure of stellar obliquities constrains the timing of hot Jupiter formation
Stars with hot Jupiters sometimes have high obliquities, which are possible relics of hot Jupiter formation. Based on the characteristics of systems with and without high obliquities, it is suspected that obliquities are tidally damped when the star has a thick convective envelope, as is the case for main-sequence star...
2201.03653v1
2022-01-22
Examining AGN UV/optical Variability Beyond the Simple Damped Random Walk
We present damped harmonic oscillator (DHO) light-curve modeling for a sample of 12,714 spectroscopically confirmed quasars in the Sloan Digital Sky Survey Stripe 82 region. DHO is a second-order continuous-time autoregressive moving-average (CARMA) process, which can be fully described using four independent parameter...
2201.08943v2
2022-02-06
Enhancing Perpendicular Magnetic Anisotropy in Garnet Ferrimagnet by Interfacing with Few-Layer WTe2
Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film is crucial in spintronic device. One way to modify the magnetic anisotropy is through the surface of the FM thin film. Here, we report the emergence of a perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in a heterostr...
2202.02834v1
2022-04-21
Characterizing the $γ$-Ray Variability of Active Galactic Nuclei with Stochastic Process Method
The $\gamma$-ray astronomy in time domain has been by now progressed further as the variabilities of Active Galactic Nuclei (AGNs) on different timescales have been reported a lot. We study the $\gamma$-ray variabilities of 23 jetted AGNs through applying a stochastic process method to the ~12.7 yr long-term light curv...
2204.09987v1
2022-04-29
A fast point charge interacting with the screened Vlasov-Poisson system
We consider the long-time behavior of a fast, charged particle interacting with an initially spatially homogeneous background plasma. The background is modeled by the screened Vlasov-Poisson equations, whereas the interaction potential of the point charge is assumed to be smooth. We rigorously prove the validity of the...
2205.00035v2
2022-05-06
Discovery of a coherent, wave-like velocity pattern for the Radcliffe Wave
Recently studies discovered that part of the Gould Belt belongs to a 2.7 kpc-long {coherent, thin} wave consisting of a chain of clouds, where a damped undulation pattern has been identified from the spatial arrangement of the clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored inside the clouds ...
2205.03218v1
2022-05-17
Resolving the HI in Damped Lyman-α systems that power star-formation
Reservoirs of dense atomic gas (primarily hydrogen), contain approximately 90 percent of the neutral gas at a redshift of 3, and contribute to 2-3 percent of the total baryons in the Universe. These damped Lyman-${\alpha}$ systems (so called because they absorb Lyman-${\alpha}$ photons from within and from background s...
2205.08554v1
2022-05-21
Accuracy of one-dimensional approximation in neutron star quasi-normal modes
Since the eigenfrequency of gravitational waves from cold neutron stars becomes a complex number, where the real and imaginary parts respectively correspond to an oscillation frequency and damping rate, one has to somehow solve the eigenvalue problem concerning the eigenvalue in two-dimensional parameter space. To avoi...
2205.10523v1
2022-06-02
Proximity of exoplanets to first-order mean-motion resonances
Planetary formation theories and, more specifically, migration models predict that planets can be captured in mean-motion resonances (MMRs) during the disc phase. The distribution of period ratios between adjacent planets shows an accumulation in the vicinity of the resonance, which is not centred on the nominal resona...
2206.00943v1
2022-06-03
Dynamical Instability in Multi-Orbiter Systems with Gas Friction
Closely-packed multi-planet systems are known to experience dynamical instability if the spacings between the planets are too small. Such instability can be tempered by the frictional forces acting on the planets from gaseous discs. A similar situation applies to stellar-mass black holes embedded in AGN discs around su...
2206.01755v1
2022-08-15
Nonperturbative approach to interfacial spin-orbit torques induced by Rashba effect
Current-induced spin-orbit torque (SOT) in normal metal/ferromagnet (NM/FM) bilayers bears great promise for technological applications, but the microscopic origin of purely interfacial SOTs in ultra-thin systems is not yet fully understood. Here, we show that a linear response theory with a nonperturbative treatment o...
2208.07296v1
2022-08-22
Plasma heating and nanoflare caused by slow-mode wave in a coronal loop
We present a detailed analysis of a reflecting intensity perturbation in a large coronal loop that appeared as sloshing oscillation and lasted for at least one and a half periods. The perturbation is initiated by a microflare at one footpoint of the loop, propagates along the loop and is eventually reflected at the rem...
2208.10029v1
2022-09-07
AlH lines in the blue spectrum of Proxima Centauri
The recently-computed ExoMol line lists for isotopologues of AlH are used to analyse the blue spectrum (4000-4500 {\AA}) of Proxima Cen (M5.5 V). Comparison of the observed and computed spectra enables the identification of a large number of 27AlH lines of the A1{\Pi} - X1{\Sigma}+ band system: the spectral range cover...
2209.03037v2
2022-09-19
Semi-implicit Integration and Data-Driven Model Order Reduction in Structural Dynamics with Hysteresis
Structural damping is known to be approximately rate-independent in many cases. Popular models for rate-independent dissipation are hysteresis models; and a highly popular hysteresis model is the Bouc-Wen model. If such hysteretic dissipation is incorporated in a refined finite element model, then the mathematical mode...
2209.08765v2
2022-10-02
Reduction in turbulence-induced non-linear dynamic vibration using tuned liquid damper (TLD)
In the present research work, an attempt is made to develop a coupled non-linear turbulence-structure-damper model in a finite volume-finite difference (FV-FD) framework. Tuned liquid damper (TLD) is used as the additional damping system along with inherent structural damping. Real-time simulation of flow-excited bridg...
2210.00428v3
2022-10-17
Interpretations of the cosmic ray secondary-to-primary ratios measured by DAMPE
Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by DAMPE show clear hardenings around $100$ GeV/n, which provide important implications on the production, propagation, and interaction of Galactic cosmic rays. In this work we investigate a number of models proposed in literature in light of the DA...
2210.09205v3
2022-10-19
Energy Dissipation in Synchronous Binary Asteroids
Synchronous binary asteroids can experience libration about their tidally-locked equilibrium, which will result in energy dissipation. This is an important topic to the Asteroid Impact and Deflection Assessment, where excitation caused by the DART kinetic impact in the Didymos binary asteroid system may be reduced thro...
2210.10877v1
2022-11-14
Heavily Damped Precessional Switching with Very Low Write-error Rate in Elliptical-cylinder Magnetic Tunnel Junction
Voltage-induced dynamic switching in magnetic tunnel junctions (MTJs) is a writing technique for voltage-controlled magnetoresistive random access memory (VCMRAM), which is expected to be an ultimate non-volatile memory with ultra-low power consumption. In conventional dynamic switching, the width of sub-nanosecond wri...
2211.07148v1
2022-11-19
Regularity to Timoshenko's System with Thermoelasticity of Type III with Fractional Damping
The article, presents the study of the regularity of two thermoelastic beam systems defined by the Timoshenko beam model coupled with the heat conduction of Green-Naghdiy theory of type III, both mathematical models are differentiated by their coupling terms that arise as a consequence of the constitutive laws initiall...
2211.10816v2
2022-12-04
An Unsupervised Machine Learning Method for Electron--Proton Discrimination of the DAMPE Experiment
Galactic cosmic rays are mostly made up of energetic nuclei, with less than $1\%$ of electrons (and positrons). Precise measurement of the electron and positron component requires a very efficient method to reject the nuclei background, mainly protons. In this work, we develop an unsupervised machine learning method to...
2212.01843v1
2022-12-05
Stability of Cnoidal Waves for the Damped Nonlinear Schrödinger Equation
We consider the cubic nonlinear Schr\"odinger (NLS) equation with a linear damping on the one dimensional torus and we investigate the stability of some solitary wave profiles within the dissipative dynamics. The undamped cubic NLS equation is well known to admit a family of periodic waves given by Jacobi elliptic func...
2212.02195v2
2022-12-08
Strong photon-magnon coupling using a lithographically defined organic ferrimagnet
We demonstrate a hybrid quantum system composed of superconducting resonator photons and magnons hosted by the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]$_x$). Our work is motivated by the challenge of scalably integrating an arbitrarily-shaped, low-damping magnetic system with planar superconductin...
2212.04423v1
2022-12-28
Scattering of the UHECR at small pitch angle by damped plasma waves
In spite a lot of theoretical and experimental effort that has been achieved in ultra-high energy cosmic ray (UHECR) scattering research in last few decades, some questions remain unanswered, or partially answered. Two of them, that will be in the focus of this paper are: possible source of UHECRs and the acceleration ...
2212.13755v1
2023-02-02
Leveraging symmetry for an accurate spin-orbit torques characterization in ferrimagnetic insulators
Spin-orbit torques (SOTs) have emerged as an efficient means to electrically control the magnetization in ferromagnetic heterostructures. Lately, an increasing attention has been devoted to SOTs in heavy metal (HM)/magnetic insulator (MI) bilayers owing to their tunable magnetic properties and insulating nature. Quanti...
2302.01141v2
2022-12-31
Genuine three qubit Einstein-Podolsky-Rosen steering under decoherence: Revealing hidden genuine steerability via pre-processing
The behaviour of genuine EPR steering of three qubit states under various environmental noises is investigated. In particular, we consider the two possible steering scenarios in the tripartite setting: (1 -> 2), where Alice demonstrates genuine steering to Bob-Charlie, and (2 -> 1), where Alice-Bob together demonstrate...
2302.02987v1
2023-02-20
Optimal energy harvesting efficiency from vortex-induced vibration of a circular cylinder under flow
This work applies a combined approach a reduced-order model (ROM) together with experiments and direct numerical simulations to investigate the optimal efficiency of fluid-flow energy harvesting from transverse vortex-induced vibration (VIV) of a circular cylinder. High resolution efficiency maps were predicted over wi...
2302.09975v1
2023-04-12
Liouvillian exceptional points in continuous variable system
The Liouvillian exceptional points for a quantum Markovian master equation of an oscillator in a generic environment are obtained. They occur at the points when the modified frequency of the oscillator vanishes, whereby the eigenvalues of the Liouvillian become real. In a generic system there are two parameters that mo...
2304.05792v2
2023-04-13
Network-Reconfiguration-Aware Power Oscillation Damping Controller for Newly Commissioned Converter-Interfaced Power Plants
In recent years, transmission system operators have started requesting converter-interfaced generators (CIGs) to participate in grid services such as power oscillation damping (POD). As power systems are prone to topology changes because of connection and disconnection of generators and electrical lines, one of the mos...
2304.06555v1
2023-06-13
Particle-resolved study of the onset of turbulence
The transition from laminar to turbulent flow is an immensely important topic that is still being studied. Here we show that complex plasmas, i.e., microparticles immersed in a low temperature plasma, make it possible to study the particle-resolved onset of turbulence under the influence of damping, a feat not possible...
2306.07711v1
2023-07-10
Vibroacoustic simulations of acoustic damping materials using a fictitious domain approach
The numerical investigation of acoustic damping materials, such as foams, constitutes a valuable enhancement to experimental testing. Typically, such materials are modeled in a homogenized way in order to reduce the computational effort and to circumvent the need for a computational mesh that resolves the complex micro...
2307.04624v1
2023-07-12
A coupled rate-dependent/rate-independent system for adhesive contact in Kirchhoff-Love plates
We perform a dimension reduction analysis for a coupled rate-dependent/rate-independent adhesive-contact model in the setting of visco-elastodynamic plates. We work with a weak solvability notion inspired by the theory of (purely) rate-independent processes, and accordingly term the related solutions `Semistable Energe...
2307.06327v1
2023-08-16
Large time asymptotics for partially dissipative hyperbolic systems without Fourier analysis: application to the nonlinearly damped p-system
A new framework to obtain time-decay estimates for partially dissipative hyperbolic systems set on the real line is developed. Under the classical Shizuta-Kawashima (SK) stability condition, equivalent to the Kalman rank condition in control theory, the solutions of these systems decay exponentially in time for high fr...
2308.08280v2
2023-08-28
The Effects of Non-Equilibrium Velocity Distributions on Alfvén Ion-Cyclotron Waves in the Solar Wind
In this work, we investigate how the complex structure found in solar wind proton velocity distribution functions (VDFs), rather than the commonly assumed two-component bi-Maxwellian structure, affects the onset and evolution of parallel-propagating microinstabilities. We use the Arbitrary Linear Plasma Solver (ALPS), ...
2308.14944v1
2023-08-31
Search for the gamma-ray spectral lines with the DAMPE and the Fermi-LAT observations
Weakly interacting massive particles, as a major candidate of dark matter (DM), may directly annihilate or decay into high-energy photons, producing monochromatic spectral lines in the gamma-ray band. These spectral lines, if detected, are smoking-gun signatures for the existence of new physics. Using the 5 years of DA...
2308.16762v1
2023-09-06
Strong magnon-magnon coupling in an ultralow damping all-magnetic-insulator heterostructure
Magnetic insulators such as yttrium iron garnets (YIGs) are of paramount importance for spin-wave or magnonic devices as their ultralow damping enables ultralow power dissipation that is free of Joule heating, exotic magnon quantum state, and coherent coupling to other wave excitations. Magnetic insulator heterostructu...
2309.03116v1
2023-09-14
A new break near 10 TeV in the energy spectrum of protons according to data from space-based instruments: astrophysical interpretation
Recent experimental data from space-based instruments of the DAMPE and CALET collaborations have shown that the energy spectrum of protons has a new feature, a break in the $\sim 10$ TeV region. In this energy range, the spectrum index of the observed particles varies from $-2.6$ to $-2.9$. The purpose of this work i...
2309.07420v1
2023-11-06
Phase mixing of propagating Alfv{é}n waves in a single-fluid partially ionized solar plasma
Phase mixing of Alfven waves is one of the most promising mechanisms for heating of the solar atmosphere. The damping of waves in this case requires small transversal scales, relative to the magnetic field direction. Here this requirement is achieved by considering a transversal inhomogeneity in the equilibrium plasma ...
2311.02989v1
2023-11-15
Damped Proximal Augmented Lagrangian Method for weakly-Convex Problems with Convex Constraints
We give a damped proximal augmented Lagrangian method (DPALM) for solving problems with a weakly-convex objective and convex linear/nonlinear constraints. Instead of taking a full stepsize, DPALM adopts a damped dual stepsize to ensure the boundedness of dual iterates. We show that DPALM can produce a (near) $\vareps$-...
2311.09065v1
2023-12-07
Nonlinear aspects of stochastic particle acceleration
In turbulent magnetized plasmas, charged particles can be accelerated to high energies through their interactions with the turbulent motions. As they do so, they draw energy from the turbulence, possibly up to the point where they start modifying the turbulent cascade. Stochastic acceleration then enters a nonlinear re...
2312.04443v2
2023-12-12
Circularization in the damped Kepler problem
In this paper, we revisit the damped Kepler problem within a general family of nonlinear damping forces with magnitude $\delta \vert u\vert^{\beta}\vert \dot u\vert^{\alpha+1}$, depending on three parameters $\delta>0,\alpha\ge 0$ and $\beta\ge 0$, and address the general question of circularization whereby orbits tend...
2312.07249v1
2023-12-21
Annealing reduces Si$_3$N$_4$ microwave-frequency dielectric loss in superconducting resonators
The dielectric loss of silicon nitride (Si$_3$N$_4$) limits the performance of microwave-frequency devices that rely on this material for sensing, signal processing, and quantum communication. Using superconducting resonant circuits, we measure the cryogenic loss tangent of either as-deposited or high-temperature annea...
2312.13504v1
2023-12-31
Molecular Hybridization Induced Antidamping and Sizable Enhanced Spin-to-Charge Conversion in Co20Fe60B20/$β$-W/C60 Heterostructures
Development of power efficient spintronics devices has been the compelling need in the post-CMOS technology era. The effective tunability of spin-orbit-coupling (SOC) in bulk and at the interfaces of hybrid materials stacking is a prerequisite for scaling down the dimension and power consumption of these devices. In th...
2401.00486v1
2024-01-11
Instability windows of relativistic r-modes
The detectability of the gravitational-wave signal from $r$-modes depends on the interplay between the amplification of the mode by the CFS instability and its damping due to dissipative mechanisms present in the stellar matter. The instability window of $r$-modes describes the region of stellar parameters (angular vel...
2401.06200v1
2024-02-06
The fermion self-energy and damping rate in a hot magnetized plasma
We derive a general expression for the fermion self-energy in a hot magnetized plasma by using the Landau-level representation. In the one-loop approximation, the Dirac structure of the self-energy is characterized by five different functions that depend on the Landau-level index $n$ and the longitudinal momentum $p_z$...
2402.04307v2
2024-04-02
A new gap in the critical exponent for semi-linear structurally damped evolution equations
Our aim in this paper is to discuss the critical exponent in semi-linear structurally damped wave and beam equations with additional dispersion term. The special model we have in mind is $$ u_{tt}(t,x)+(-\Delta)^{\sigma}u(t,x)+(-\Delta)^{2\delta}u(t,x)+2(-\Delta)^{\delta}u_{t}(t,x)=\left|u(t,x)\right| ^{p} $$ where the...
2404.01544v1
2024-04-10
Quantum algorithms to simulate quadratic classical Hamiltonians and optimal control
Simulation of realistic classical mechanical systems is of great importance to many areas of engineering such as robotics, dynamics of rotating machinery and control theory. In this work, we develop quantum algorithms to estimate quantities of interest such as the kinetic energy in a given classical mechanical system i...
2404.07303v1
1999-07-23
Autoregressive model of 1/f noise
An analytically solvable model is proposed exhibiting 1/f spectrum in any desirably wide range of frequency (but excluding the point f=0). The model consists of pulses whose recurrence times obey an autoregressive process with very small damping.
9907008v1
1996-08-22
Evolution of Neutral Gas at High Redshift -- Implications for the Epoch of Galaxy Formation
Though observationally rare, damped Lya absorption systems dominate the mass density of neutral gas in the Universe. Eleven high redshift damped Lya systems covering 2.8<z<4.4 were discovered in 26 QSOs from the APM z>4 QSO Survey, extending these absorption system surveys to the highest redshifts currently possible. C...
9608147v1
1997-07-14
Damped Lyman-alpha Absorption Associated with an Early-Type Galaxy at Redshift z = 0.16377
We report new HST and ground-based observations of a damped Lyman-alpha absorption system toward the QSO 0850+4400. The redshift of the absorption system is z = 0.163770 and the neutral hydrogen column density of the absorption system is log N = 19.81 cm**-2. The absorption system is by far the lowest redshift confirme...
9707157v1
1997-08-27
Reionization of the Intergalactic Medium and the Damping Wing of the Gunn-Peterson Trough
Observations of high-redshift quasars show that the IGM must have been reionized at some redshift $z>5$. If a source of radiation could be observed at the rest-frame Lya wavelength, at a sufficiently high redshift where some of the IGM in the line-of-sight was not yet reionized, the Gunn-Peterson trough should be prese...
9708253v1
1997-09-16
On the nature of z(abs) ~ z(em) damped absorbers in quasar spectra
We present spectroscopic observations of the damped Ly-alpha absorber at redshift z=1.9342 seen in the spectrum of the quasar Q0151+048A. The redshift of the absorber is greater than the redshift of the quasar, so the system resembles the z(abs) ~ z(em) damped absorber at z=2.81 towards the quasar PKS0528-250. We have ...
9709160v1
1998-01-15
A HST Spectroscopic study of QSOs with intermediate redshift damped Lyman-alpha systems
We present HST spectra for a sample of six QSOs with intermediate redshift (z_a < 1) damped Ly-alpha systems. These observations aim at measuring the HI column density and detect metal lines in order to investigate the metal enrichment of the gas, as well as the presence of neutral species, molecules and dust. All syst...
9801146v1
1998-06-15
On the kinematics of damped Lyman-alpha systems
We report on high spectral resolution observations of five damped Ly-alpha absorbers. Line velocity profiles and heavy element abundances are discussed. Nitrogen is found to have abundances less than silicon in the systems toward Q 0347-383, Q 0913+072, and Q 1213+093. The absorber toward Q 0913+072 is the most metal-d...
9806202v1
1999-10-07
Si and Mn Abundances in Damped Lya Systems with Low Dust Content
We have measured the abundances of Zn, Si, Mn, Cr, Fe, and Ni in three damped Lyman alpha systems at redshifts z < 1 from high resolution echelle spectra of QSOs recorded with the Keck I telescope. In all three cases the abundances of Cr, Fe, and Ni relative to Zn indicate low levels of dust depletions. We propose that...
9910131v1
1999-11-23
On the orbital evolution and growth of protoplanets embedded in a gaseous disc
We present a new computation of the linear tidal interaction of a protoplanetary core with a thin gaseous disc in which it is fully embedded. For the first time a discussion of the orbital evolution of cores with eccentricity (e) significantly larger than the gas-disc scale height to radius ratio (H/r) is given. We fin...
9911431v1
1999-12-14
Finding typical high redshift galaxies with the NOT
We present results from an ongoing search for galaxy counterparts of a subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers (DLAs). DLAs have several characteristics that make them prime candidates for being the progenitors of typical present day galaxies.
9912278v1
2000-10-21
UVES observations of QSO 0000-2620: Argon and Phosphorus abundances in the dust-free damped Ly-alpha system at zabs = 3.3901
The UV resonance transitions of neutral argon ArI 1066 A, and of singly ionized phosphorus PII 963 A, originated in the damped Ly_alpha system (DLA) at zabs = 3.3901 towards QSO 0000--2620 have been detected by means of the UVES spectrograph at the 8.2m ESO KUEYEN telescope. So far, this is the first measurement of ArI...
0010434v1
2001-09-21
Coincidences of high density peaks in UVES spectra of QSO pairs
We present preliminary results of an investigation of the clustering properties of high matter density peaks between redshift ~2 and ~3, as traced by Lyman limit and Damped Ly-alpha systems in spectra of close QSO pairs and groups.
0109373v1
2002-01-31
Electron impact excitation of helium-like oxygen up to n = 4 levels including radiation damping
The primary X-ray diagnostic lines in He-like ions are mainly excited by electron impact from the ground level to the n = 2 levels, but at high temperatures n > 2 levels are also excited. In order to describe the atomic processes more completely collision strengths are computed for OVII including for the first time all...
0201535v1
2002-12-07
Improved Bounds on Violation of the Strong Equivalence Principle
I describe a unique, 20-year-long timing program for the binary pulsar B0655+64, the stalwart control experiment for measurements of gravitational radiation damping in relativistic neutron-star binaries. Observed limits on evolution of the B0655+64 orbit provide new bounds on the existence of dipolar gravitational radi...
0212180v1
2006-01-23
Bulk viscosity of a gas of neutrinos and coupled scalar particles, in the era of recombination
Bulk viscosity may serve to damp sound waves in a system of neutrinos coupled to very light scalar particles, in the era after normal neutrino decoupling but before recombination. We calculate the bulk viscosity parameter in a minimal scheme involving the coupling of the two systems. We add some remarks on the bulk vis...
0601525v1
2006-09-28
Turbulent Comptonization in Relativistic Accretion Disks
Turbulent Comptonization, a potentially important damping and radiation mechanism in relativistic accretion flows, is discussed. Particular emphasis is placed on the physical basis, relative importance, and thermodynamics of turbulent Comptonization. The effects of metal-absorption opacity on the spectral component res...
0609797v1
1994-05-16
Bifurcations of two coupled classical spin oscillators
Two classical, damped and driven spin oscillators with an isotropic exchange interaction are considered. They represent a nontrivial physical system whose equations of motion are shown to allow for an analytic treatment of local codimension 1 and 2 bifurcations. In addition, numerical results are presented which exhibi...
9405011v1
1998-04-02
The Decay Properties of the Finite Temperature Density Matrix in Metals
Using ordinary Fourier analysis, the asymptotic decay behavior of the density matrix F(r,r') is derived for the case of a metal at a finite electronic temperature. An oscillatory behavior which is damped exponentially with increasing distance between r and r' is found. The decay rate is not only determined by the elect...
9804013v1
1998-12-02
Dissipative properties of vibrated granular materials
We investigate collective dissipative properties of vibrated granular materials by means of molecular dynamics simulations. Rates of energy losses indicate three different regimes or "phases"in the amplitude-frequency plane of the external forcing, namely, solid, convective, and gas-like regimes. The behavior of effect...
9812036v1
1999-01-14
Spin dynamics in the generalized ferromagnetic Kondo model for manganites
Dynamical spin susceptibility is calculated for the generalized ferromagnetic Kondo model which describes itinerant $e_{g}$ electrons interacting with localized $t_{2g}$ electrons with antiferromagnetic coupling. The calculations done in the mean field approximation show that the spin-wave spectrum of the system in fer...
9901141v1
1999-10-01
Properties of excitations in systems with a spinor Bose-Einstein condensate
General theory in case of homogenous Bose-Einstein condensed systems with spinor condensate is presented for the correlation functions of density and spin fluctuations and for the one-particle propagators as well. The random phase approximation is investigated and the damping of the modes is given in the intermediate t...
9910010v1
2001-07-16
Anomalous Levy decoherence
We investigate the decoherence of a small quantum system weakly coupled to a complex, chaotic environment when the dynamics is not Gaussian but Levy anomalous. By studying the time dependence of the linear entropy and the damping of the interference of two Gaussian wave packets in the Wigner representation, we show tha...
0107344v1
2002-03-06
Effect of electron-phonon interaction on the shift and attenuation of optical phonons
Using the Boltzmann equation for electrons in metals, we show that the optical phonons soften and have a dispersion due to screening in agreement with the results reported recently [M. Reizer, Phys. Rev. B {\bf 61}, 40 (2000)]. Additional phonon damping and frequency shift arise when the electron--phonon interaction is...
0203112v1
2002-04-09
Spatial resolution of spin waves in an ultra-cold gas
We present the first spatially resolved images of spin waves in a gas. The complete longitudinal and transverse spin field as a function of time and space is reconstructed. Frequencies and damping rates for a standing-wave mode are extracted and compared with theory.
0204182v1
2002-08-14
Three-wave mixing of Bogoliubov quasi-particles in a Bose condensate
A dressed basis is used to calculate the dynamics of three-wave mixing between Bogoliubov quasi-particles in a Bose condensate. Due to the observed oscillations between different momenta modes, an energy splitting, analogous to the optical Mollow triplet, appears in the Beliaev damping spectrum of the excitations from ...
0208283v2
2002-11-08
Reply on ``Fluctuation-dissipation considerations for phenomenological damping models for ferromagnetic thin films'' [N. Smith, J. Appl. Phys. \bf{92}, 3877 (2002)]
We show that the critique of our recent papers presented in the abovementioned paper (NS) appeals to an incorrect mathematical analogy between electrical circuits and linear magnetization dynamics, improperly uses classical concepts of normal modes and basic equations, gives inconsistent results and therefore comes to ...
0211147v1
2003-02-04
Squeezing and temperature measurement in Bose-Einstein Condensates
In this paper we discuss the presence of temperature-dependent squeezing in the collective excitations of trapped Bose-Einstein condensates, based on a recent theory of quasiparticle damping. A new scheme to measure temperature below the critical temperature is also considered.
0302068v1
2003-03-12
Time-Dependent Dynamics of the Bose-Fermi Mixed Condensed System
We study the monopole oscillation in the bose-fermi mixed condensed system by performing the time-dependent Gross-Pitaevsky (GP) and Vlasov equations. We find that the big damping exists for the fermion oscillation in the mixed system even at zero temperature
0303216v1
2005-10-06
Thermal processes induced in carbon nanotubes by attosecond laser pulses
In this paper the heat transport in carbon nanotubes is investigated. When the dimension of the structure is of the order of the de Broglie wave length the transport phenomena must be analyzed within quantum mechanics. In this paper we developed the Dirac type thermal equation. The solution of the equation the temperat...
0510141v1
2006-08-22
Simulation of stress-impedance effects in low magnetostrictive films
A theoretical study of stress-impedance effect based on the solution of Landau-Lifsitz-Gilbert equation has been carried out. The results show that stress impedance effects depend largely on several extrinsic (external bias field, external frequency) and intrinsic (orientation and magnitude of uniaxial anisotropy, damp...
0608488v1
2006-09-05
Lifetimes of electrons in the Shockley surface state band of Ag(111)
We present a theoretical many-body analysis of the electron-electron (e-e) inelastic damping rate $\Gamma$ of electron-like excitations in the Shockley surface state band of Ag(111). It takes into account ab-initio band structures for both bulk and surface states. $\Gamma$ is found to increase more rapidly as a functio...
0609080v1
2006-09-28
Transition-Event Durations in One Dimensional Activated Processes
Despite their importance in activated processes, transition-event durations -- which are much shorter than first passage times -- have not received a complete theoretical treatment. We therefore study the distribution of durations of transition events over a barrier in a one-dimensional system undergoing over-damped La...
0609741v1
2007-01-08
Coefficient of restitution for viscoelastic disks
The dissipative collision of two identical viscoelastic disks is studied. By using a known law for the elastic part of the interaction force and the viscoelastic damping model an analytical solution for the coefficient of restitution shall be given. The coefficient of restitution depends significantly on the impact vel...
0701142v1
2007-01-09
Enhanced Weiss oscillations in graphene
The magneto-conductivity of a single graphene layer where the electrons are described by the Dirac Hamiltonian weakly modulated by a periodic potential is calculated. It is shown that Weiss oscillations periodic in the inverse magnetic field appear, that are more pronounced and less damped with the increment of tempera...
0701175v1
2007-03-15
A new electromagnetic mode in graphene
A new, weakly damped, {\em transverse} electromagnetic mode is predicted in graphene. The mode frequency $\omega$ lies in the window $1.667<\hbar\omega/\mu<2$, where $\mu$ is the chemical potential, and can be tuned from radiowaves to the infrared by changing the density of charge carriers through a gate voltage.
0703406v1
1997-04-01
Controversies in the History of the Radiation Reaction problem in General Relativity
This paper examines the historical controversy over whether gravitationally bound systems, such as binary stars, experienced orbital damping due to the emission of gravitational radiation, focusing especially on the period of the 1950s, but also discussing the work of Einstein and Rosen in the 1930s on cylindrical grav...
9704002v1