publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
|---|---|---|---|
2020-09-28 | Comparison of proton shower developments in the BGO calorimeter of the Dark Matter Particle Explorer between GEANT4 and FLUKA simulations | The DArk Matter Particle Explorer (DAMPE) is a satellite-borne detector for
high-energy cosmic rays and $\gamma$-rays. To fully understand the detector
performance and obtain reliable physical results, extensive simulations of the
detector are necessary. The simulations are particularly important for the data
analysis ... | 2009.13036v1 |
2021-01-19 | Sub-damped Lyman alpha systems in the XQ-100 survey II -- Chemical evolution at 2.4<z<4.3 | We present the measured gas-phase metal column densities in 155 sub-damped
Lyman alpha systems (subDLAs) with the aim to investigate the contribution of
subDLAs to the chemical evolution of the Universe. The sample was identified
within the absorber-blind XQ-100 quasar spectroscopic survey over the redshift
range 2.4<=... | 2101.07821v1 |
2021-04-24 | Compressive oscillations in hot coronal loops: Are sloshing oscillations and standing slow waves independent? | Employing high-resolution EUV imaging observations from SDO/AIA, we analyse a
compressive plasma oscillation in a hot coronal loop triggered by a C-class
flare near one of its foot points as first studied by Kumar et al. We
investigate the oscillation properties in both the 131{\,}{\AA} and 94{\,}{\AA}
channels and fin... | 2104.12038v1 |
2021-08-09 | Synchronization of Power Systems under Stochastic Disturbances | The synchronization of power generators is an important condition for the
proper functioning of a power system, in which the fluctuations in frequency
and the phase angle differences between the generators are sufficiently small
when subjected to stochastic disturbances. Serious fluctuations can prompt
desynchronizatio... | 2108.04667v2 |
2021-10-12 | Two-body collapse model for self-gravitating flow of dark matter and generalized stable clustering hypothesis for pairwise velocity | Analytical tools are extremely hard to find for non-linear gravitational
collpase. Only a few simple but powerful tools exist so far. Two examples are
the spherical collapse model (SCM) and stable clustering hypothesis (SCH). We
present a new analytical tool, a two-body collapse model (TBCM), that plays the
same fundam... | 2110.05784v2 |
2021-10-25 | Capillary gravity water waves linearized at monotone shear flows: eigenvalues and inviscid damping | This paper is concerned with the eigenvalues and linear inviscid damping of
the 2D capillary gravity water waves of finite depth $x_2\in(-h,0)$ linearized
at a monotone shear flow $U(x_2)$. Unlike the linearized Euler equation in a
fixed channel where eigenvalues exist only in low horizontal wave number $k$,
we first p... | 2110.12604v3 |
2021-12-01 | Damped Ly-alpha Absorbers in Star-forming Galaxies at z < 0.15 Detected with the Hubble Space Telescope and Implications for Galaxy Evolution | We report {\it HST} COS spectroscopy of 10 quasars with foreground
star-forming galaxies at 0.02$<$$z$$<$ 0.14 within impact parameters of
$\sim$1-7 kpc. We detect damped/sub-damped Ly$\alpha$ absorption in 100$\%$ of
cases where no higher-redshift Lyman-limit systems extinguish the flux at the
expected wavelength of L... | 2112.00870v1 |
2022-01-06 | Parameter-free quantum hydrodynamic theory for plasmonics: Electron density-dependent damping rate and diffusion coefficient | Plasmonics is a rapid growing field, which has enabled both fundamental
science and inventions of various quantum optoelectronic devices. An accurate
and efficient method to calculate the optical response of metallic structures
with feature size in the nanoscale plays an important role. Quantum
hydrodynamic theory (QHT... | 2201.03426v3 |
2022-01-12 | Neutrino effective potential and damping in a fermion and scalar background in the resonance region | We consider the propagation of a neutrino or an antineutrino in a medium
composed of fermions $f$ and scalars $\phi$ interacting via a Yukawa-type
coupling of the form $\bar f\nu\phi$, for neutrino energies at which the
processes like $\nu + \phi \leftrightarrow f$ or $\nu + \bar f \leftrightarrow
\bar\phi$, and the co... | 2201.04661v2 |
2022-01-19 | Transverse Coronal-Loop Oscillations Induced by the Non-radial Eruption of a Magnetic Flux Rope | We investigate the transverse coronal-loop oscillations induced by the
eruption of a prominence-carrying flux rope on 7 December 2012. The flux rope
originating from NOAA Active Region (AR) 11621 was observed in EUV wavelengths
by the SDO/AIA and in H$\alpha$ line center by the ground-based telescope at
the BBSO. The e... | 2201.07389v1 |
2022-03-16 | Snowmass Whitepaper AF6: Plasma-Based Particle Sources | High-brightness beams generated by particle sources based on advanced
accelerator concepts have the potential to become an essential part of future
accelerator technology. High-gradient accelerators can generate and rapidly
accelerate particle beams to relativistic energies while minimizing
irreversible detrimental eff... | 2203.08379v2 |
2022-04-04 | Staring at the Shadows of Archaic Galaxies: Damped Ly$α$ and Metal Absorbers toward a Young $z \sim 6$ Weak-line Quasar | We characterize the Ly$\alpha$ halo and absorption systems toward PSO
J083+11, a unique $z=6.3401$ weak-line quasar, using Gemini/GNIRS,
Magellan/FIRE, and VLT/MUSE data. Strong absorptions by hydrogen and several
metal lines (e.g., CII, MgII, and OI) are discovered in the spectrum, which
indicates the presence of: (i)... | 2204.01245v2 |
2022-04-28 | Viscous inertial modes on a differentially rotating sphere: Comparison with solar observations | In a previous paper we studied the effect of latitudinal rotation on solar
equatorial Rossby modes in the beta-plane approximation. Since then, a rich
spectrum of inertial modes has been observed on the Sun, which is not limited
to the equatorial Rossby modes and includes high-latitude modes.
Here we extend the compu... | 2204.13412v1 |
2022-10-18 | Magnetohydrodynamic instabilities in a self-gravitating rotating cosmic plasma | The generation of magnetohydrodynamic (MHD) waves and their instabilities are
studied in galactic gaseous rotating plasmas with the effects of the magnetic
field, the self gravity, the diffusion-convection of cosmic rays as well as the
gas and cosmic-ray pressures. The coupling of the Jeans, Alfv{\'e}n and
magnetosonic... | 2210.09595v1 |
2023-04-17 | Theoretical study of the Alfven Eigenmode stability in CFETR steady state discharges | The aim of this study is to analyze the stability of Alfven Eigenmodes (AE)
in the China Fusion Engineering Test Reactor (CFETR) plasma for steady state
operations. The analysis is done using the gyro-fluid code FAR3d including the
effect of the acoustic modes, EP Finite Larmor radius damping effects and
multiple energ... | 2304.08412v1 |
2023-05-21 | Small-amplitude Compressible Magnetohydrodynamic Turbulence Modulated by Collisionless Damping in Earth's Magnetosheath: Observation Matches Theory | Plasma turbulence is a ubiquitous dynamical process that transfers energy
across many spatial and temporal scales and affects energetic particle
transport. Recent advances in the understanding of compressible
magnetohydrodynamic (MHD) turbulence demonstrate the important role of damping
in shaping energy distributions ... | 2305.12507v3 |
2023-07-14 | PIC simulations of stable surface waves on a subcritical fast magnetosonic shock front | We study with particle-in-cell (PIC) simulations the stability of fast
magnetosonic shocks. They expand across a collisionless plasma and an
orthogonal magnetic field that is aligned with one of the directions resolved
by the 2D simulations. The shock speed is 1.6 times the fast magnetosonic speed
when it enters a laye... | 2307.07435v1 |
2023-08-03 | Part I: Rebuttal to "Uniform stabilization for the Timoshenko beam by a locally distributed damping" | A paper, entitled "Uniform stabilization for the Timoshenko beam by a locally
distributed damping" was published in 2003, in the journal Electronic Journal
of Differential Equations. Its title concerns exclusively its Section 3,
devoted to the case of equal speeds of propagation and to its main theorem,
namely Theorem ... | 2308.01611v1 |
2023-09-01 | f-mode oscillations of anisotropic neutron stars in full general relativity | We investigate f-mode oscillations of static anisotropic stable neutron stars
within the framework of full general relativity. We present equations governing
unperturbed stellar structures and oscillations with an ansatz to account for
the anisotropy. We solve those equations for two different equations of states.
We s... | 2309.00439v2 |
2023-09-10 | Stability and Regularity for Double Wall Carbon Nanotubes Modeled as Timoshenko Beams with Thermoelastic Effects and Intermediate Damping | This research studies two systems composed by the Timoshenko beam model for
double wall carbon nanotubes, coupled with the heat equation governed by
Fourier's law. For the first system, the coupling is given by the speed the
rotation of the vertical filament in the beam $\beta\psi_t$ from the first beam
of Tymoshenko a... | 2309.04906v1 |
2023-11-03 | Probing the disc-jet coupling in S4 0954+65, PKS 0903-57, & 4C +01.02 with $γ$-rays | We present a comprehensive variability study on three blazars, S4 0954+65,
PKS 0903-57, and 4C +01.02 covering a mass range of log(M/M$_{\odot}$) = 8--9,
by using $\sim$15 years-long $\gamma$-ray light curves from \textit{Fermi}-LAT.
The variability level is characterized by the fractional variability amplitude
which i... | 2311.01738v1 |
2023-11-30 | Compton scattering of electrons in the intergalactic medium | This paper investigates the distribution and implications of cosmic ray
electrons within the intergalactic medium (IGM). Utilizing a synthesis model of
the extragalactic background, we evolve the spectrum of Compton-included cosmic
rays. The energy density distribution of cosmic ray electrons peaks at redshift
$z \appr... | 2311.18721v2 |
2024-01-18 | Chronicling the reionization history at $6\lesssim z \lesssim 7$ with emergent quasar damping wings | The spectra of high-redshift ($z\gtrsim 6$) quasars contain valuable
information on the progression of the Epoch of Reionization (EoR). At redshifts
$z<6$, the observed Lyman-series forest shows that the intergalactic medium
(IGM) is nearly ionized, while at $z>7$ the observed quasar damping wings
indicate high neutral... | 2401.10328v1 |
2024-03-04 | Exploring Standing and Reflected Slow-mode Waves in Flaring Coronal Loops: A Parametric Study Using 2.5D MHD Modeling | Recent observations of reflected propagating and standing slow-mode waves in
hot flaring coronal loops have spurred our investigation into their underlying
excitation and damping mechanisms. To understand these processes, we conduct
2.5D magnetohydrodynamic (MHD) simulations using an arcade active region model
that inc... | 2403.02464v1 |
2024-04-05 | Searching for Emission Lines at $z>11$: The Role of Damped Lyman-$α$ and Hints About the Escape of Ionizing Photons | We describe new ultra-deep James Webb Space Telescope (JWST) NIRSpec PRISM
and grating spectra for the galaxies JADES-GS-z11-0 ($z_{\mathrm{spec}} =
11.122^{+0.005}_{-0.003}$) and JADES-GS-z13-0 ($z_{\mathrm{spec}} =
13.20^{+0.03}_{-0.04}$), the most distant spectroscopically-confirmed galaxy
discovered in the first ye... | 2404.04325v1 |
2022-04-17 | Sharper Bounds on Four Lattice Constants | The Korkine--Zolotareff (KZ) reduction, and its generalisations, are widely
used lattice reduction strategies in communications and cryptography. The KZ
constant and Schnorr's constant were defined by Schnorr in 1987. The KZ
constant can be used to quantify some useful properties of KZ reduced matrices.
Schnorr's const... | 2204.08021v1 |
1998-09-23 | An Unexpected Electrovac Solution with the Negative Cosmological Constant | An exact solution of the current-free Einstein-Maxwell equations with the
cosmological constant is presented. The solution is of Petrov type D, includes
the negative cosmological constant, and could be a ``background addition'' to
the present-day models of the universe. It has a surprising property such that
its electr... | 9809066v2 |
2006-05-24 | New Universal Flavor-Electroweak Physical Constant and Neutrino Type | By analogy with the solution of the classical physics problems achieved not
by an extension of the established dynamic and symmetry knowledge but by the
emergence of a fundamentally new empirical physical constant h leading to
quantum mechanics, I address in this paper the known basic problems of lepton
mass ratios, ne... | 0605267v6 |
2023-11-10 | Robust Constant-Time Cryptography | The constant-time property is considered the security standard for
cryptographic code. Code following the constant-time discipline is free from
secret-dependent branches and memory accesses, and thus avoids leaking secrets
through cache and timing side-channels. The constant-time property makes a
number of implicit ass... | 2311.05831v1 |
2023-11-24 | Constant-Time Wasmtime, for Real This Time: End-to-End Verified Zero-Overhead Constant-Time Programming for the Web and Beyond | We claim that existing techniques and tools for generating and verifying
constant-time code are incomplete, since they rely on assumptions that compiler
optimization passes do not break constant-timeness or that certain operations
execute in constant time on the hardware. We present the first end-to-end
constant-time-a... | 2311.14246v1 |
1994-11-01 | Symplectic Computation of Lyapunov Exponents | A recently developed method for the calculation of Lyapunov exponents of
dynamical systems is described. The method is applicable whenever the
linearized dynamics is Hamiltonian. By utilizing the exponential representation
of symplectic matrices, this approach avoids the renormalization and
reorthogonalization procedur... | 9411001v1 |
1993-10-28 | Modes of Elliptical Galaxies | Long lived modes of elliptical galaxies can exist {\it \`a la} van Kampen.
Specific systems may possess long lived oscillations which Landau damp on time
scales longer than a Hubble time. Some physical processes such as a close
encounter, tidal forces from a cluster or an orbiting satellite could
preferentially excite ... | 9310050v1 |
1994-12-19 | Massive Neutrinos and Galaxy Formation | We report the most recent results from high-resolution numerical simulations
of structure formation in two flat cold+hot dark matter models with neutrino
mass densities $\onu=0.2$ and 0.3. We find that structure forms too late in all
CDM+HDM models with $\onu>0.2$ to account for the amount of dense neutral gas
in high-... | 9412068v1 |
1995-01-30 | Element Abundances at High Redshifts: The N/O Ratio at Low Metallicity | Our knowledge of galactic chemical evolution is currently limited to
observations of Milky Way stars and H II regions of nearby galaxies. Damped
Lyman~$\alpha$ systems offer a new approach for tracking the evolution of
normal galaxies from early epochs to the present day. Here we report the first
measurements of nitrog... | 9501105v1 |
1996-06-21 | Measuring the Curvature of the Universe | We discuss how the curvature of the universe can be robustly measured
employing only the gross features of the CMB anisotropy spectrum. Though the
position of the first peak is not robust, uncertainties in the model for
structure formation can be removed by using the spacing of the acoustic peaks
and the location of th... | 9606140v1 |
1996-10-24 | Small-angle anisotropies in the CMBR from active sources | We consider the effects of photon diffusion on the small-angle microwave
background anisotropies due to active source models. We find that fluctuations
created just before the time of last scattering allow anisotropy to be created
on scales much smaller than allowed by standard Silk damping. Using simple
models for str... | 9610197v1 |
1996-11-06 | Interactions Between Massive Dark Halos And Warped Disks | The normal mode theory for warping of galaxy disks, in which disks are
assumed to be tilted with respect to the equator of a massive, flattened dark
halo, assumes a rigid, fixed halo. However, consideration of the back-reaction
by a misaligned disk on a massive particle halo shows there to be strong
coupling leading to... | 9611050v1 |
1996-11-19 | Reheating and causal thermodynamics | The reheating process in inflationary universe models is considered as an
out-of-equilibrium mixture of two interacting and reacting fluids, and studied
within the framework of causal, irreversible thermodynamics. The evolution of
the temperature and the decay rate as determined by causal thermodynamics are
estimated a... | 9611147v1 |
1996-12-04 | UV HST Spectroscopy of Star-Forming Galaxies | HST spectroscopical observations of 8 HII galaxies are reported. Ly alpha
emission was detected in 4 of them. We find that the velocity structure of the
gas is the main determining factor for the escape of the Ly alpha photons, and
not the abundance of dust. The rest of the sample shows broad damped Ly alpha
absorption... | 9612043v1 |
1996-12-05 | Modified Artificial Viscosity in Smooth Particle Hydrodynamics | Artificial viscosity is needed in Smooth Particle Hydrodynamics to prevent
interparticle penetration, to allow shocks to form and to damp post shock
oscillations. Artificial viscosity may, however, lead to problems such as
unwanted heating and unphysical solutions. A modification of the standard
artificial viscosity re... | 9612050v2 |
1997-02-16 | Barnett Relaxation in Thermally-Rotating Grains | We present an exact formulation of the physics of Barnett relaxation. Our
formulation is based on a realistic kinetic model of the relaxation mechanism
which includes the alignment of the grain angular momentum in body coordinates
by Barnett dissipation, disalignment by thermal fluctuations, and coupling of
the angular... | 9702138v1 |
1997-04-16 | Gravitational Waves from Phase Transition of Accreting Neutron Stars | We propose that when neutron stars in low-mass X-ray binaries accrete
sufficient mass and become millisecond pulsars, the interiors of these stars
may undergo phase transitions, which excite stellar radial oscillations. We
show that the radial oscillations will be mainly damped by gravitational-wave
radiation instead o... | 9704161v1 |
1997-07-08 | Collisionless Relaxation in Galactic Dynamics and the Evolution of Long Range Order | This talk provides a critical assessment of collisionless galactic dynamics,
focusing on the interpretation and limitations of the collisionless Boltzmann
equation and the physical mechanisms associated with collisionless relaxation.
Numerical and theoretical arguments are presented to motivate the idea that the
evolut... | 9707103v1 |
1997-10-31 | On Breaking Cosmic Degeneracy | It has been argued that the power spectrum of the anisotropies in the Cosmic
Microwave Background (CMB) may be effectively degenerate, namely that the
observable spectrum does not determine a unique set of cosmological parameters.
We describe the physical origin of this degeneracy and show that at small
angular scales ... | 9710364v1 |
1998-01-05 | Model Predictions for Clustering and Morphologies at HDF depths | The current status of numerical simulations of the formation of galaxies is
reviewed. Success and failure of modeling galaxies at low and high redshift is
demonstrated using a variety of examples, such as the Tully-Fisher relation,
the appearance of high-redshift galaxies and the kinematics of damped Lya
systems. The r... | 9801025v1 |
1998-05-26 | Do Soft Gamma Repeaters Emit Gravitational Waves? | Soft gamma repeaters are identified as highly magnetized (B$\approx 10^{14}$
Gauss) neutron stars. Magnetic stresses induce tectonic activity, and field
annihilation in faults is the ultimate energy source for the observed
$\gamma$-ray emission. As a consequence of the crustal cracking, the stored
elastic energy is con... | 9805321v1 |
1998-06-29 | The impact on cosmology of a primordial scaling field | A scalar field with an exponential potential has the particular property that
it is attracted into a solution in which its energy scales as the dominant
component (radiation or matter) of the Universe, contributing a fixed fraction
of the total energy density. We briefly discuss the dynamics of such a scalar
field and ... | 9806373v1 |
2000-01-05 | Cold gas, the HI 21cm line and evolving galactic potentials | Neutral hydrogen traces gravitational potentials. In the nearby universe,
21cm emission-line surveys show that the bulk of the HI resides in well-formed,
optically-luminous galaxies. At high redshift, 21cm line absorption against
background radio quasars occurs in gas-rich systems identified with the highest
HI column ... | 0001070v1 |
2000-01-19 | Stochastic Acceleration and Non-Thermal Radiation in Clusters of Galaxies | We calculate the distribution of electrons in clusters of galaxies, resulting
from thermalization processes in the presence of stochastic acceleration due to
plasma waves. We show that the electron distribution can deviate from a
Maxwell-Boltzmann distribution, due to the effect of the stochastic energy
gain, provided ... | 0001344v1 |
2000-02-29 | Models of Wave Supported Clumps in Giant Molecular Clouds | We present plane-parallel equilibrium models of molecular clumps that are
supported by Alfven waves damped by the linear process of ion-neutral friction.
We used a WKB approximation to treat the inward propagation of waves and
adopted a realistic ionization structure influenced by dissociation and
ionization due to pho... | 0002531v1 |
2000-03-20 | Old models for Cygnus X-1 and AGN | Recently, there appeared many papers devoted to the modeling of X-ray
properties of Cygnus X-1 and other black hole accretion disk candidates: e.g.
J.Poutanen, J.Krolik, F.Ryde, MNRAS 292 (1997) L21; E.Agol, J.Krolik, ApJ 507
(1998) 304; A.Beloborodov, in ``High Energy Processes in Accreting Black
Holes'', ASP Conf. Se... | 0003275v1 |
2000-05-08 | X-ray Fluctuations from the Slim Disk | The responses of perturbations added into the optically thick,
advection-dominated accretion disk (ADAD), what we call the slim disk (SD), are
investigated through numerical simulations. Although it is proposed that the SD
is thermally stable, I find that a perturbation added into the disk is not
rapidly damped and mov... | 0005162v1 |
2000-10-18 | Disks at High Redshift: Interactions, Mergers, and Starbursts | Do disk galaxies exist at redshifts much greater than unity, and how might
they look different from local disks? How does the morphological mix of
galaxies change with redshift? What can we learn from current observations
about the properties of high redshift galactic disks? I present theoretical
predictions based on s... | 0010350v1 |
2001-01-10 | Fast Zonal Field Dynamo in Collisionless Kinetic Alfven Wave Turbulence | The possibility of fast dynamo action by collisionless kinetic Alfven Wave
turbulence is demonstrated. The irreversibility necessary to lock in the
generated field is provided by electron Landau damping, so the induced electric
field does not vanish with resistivity. Mechanisms for self-regulation of the
system and the... | 0101159v1 |
2001-09-27 | The theory of CMB anisotropies | This is a review of the theory of CMB anisotropies, an updated version of a
course given at the troisieme cycle de la Suisse Romande. An introduction to
gauge invariant cosmological perturbation theory is given and the theory CMB
anisotropies is develiped in this context. Simple analytical approximations for
the acoust... | 0109522v1 |
2001-11-30 | Chemical Abundances in High-Redshift Neutral Clouds | Neutral hydrogen clouds with high column density detected towards distant
quasars are unique probes of elemental nucleosynthesis and chemical evolution
in the low metallicity regime. They provide measurements for several elements
at very early times which are unfeasible in other astrophysical environments.
Comparison b... | 0111592v1 |
2001-12-21 | Quasar Absorption Lines | The absorption lines observed in quasar spectra have given us a detailed
picture of the intergalactic medium and the metal abundance and kinematics of
high redshift galaxies. In this review, we present an introduction to the
field, starting with the techniques used for interpreting absorption line
spectra. We then surv... | 0112521v1 |
2002-01-25 | Numerical studies of galaxy formation using special purpose hardware | I review recent progress in numerically simulating the formation and
evolution of galaxies in hierarchically clustering universes. Special emphasis
is given to results based on high-resolution gas dynamical simulations using
the N-body hardware integrator GRAPE. Applications address the origin of the
spin of disk galax... | 0201427v1 |
2002-09-10 | Extrasolar Planets and Mean-Motion Resonances | The 2:1 orbital resonances of the GJ 876 system can be easily established by
the differential planet migration due to planet-nebula interaction. Significant
eccentricity damping is required to produce the observed orbital
eccentricities. The geometry of the GJ 876 resonance configuration differs from
that of the Io-Eur... | 0209176v1 |
2002-09-17 | Discrimination of Quark Stars from Neutron Stars in Quadrupole Oscillations | The frequencies and damping times due to gravitational radiation are
calculated for self-bound quark star models. The results are compared with
those for neutron star models. They are markedly contrasted in less
relativistic cases. The distinction derived here from a simple model of quark
stars may be relevant to the f... | 0209320v1 |
2002-09-30 | Perspectives in Galactic Chemical Evolution studies | In this review I focus on a few selected topics, where recent theoretical
and/or observational progress has been made and important developments are
expected in the future. They include: 1) Evolution of isotopic ratios, 2)
Mixing processes and dispersion in abundance ratios, 3) Abundance gradients in
the Galactic disk ... | 0209620v1 |
2003-04-10 | Challenges in generating density perturbations from a fluctuating inflaton coupling | We discuss the possibility of generating adiabatic density perturbations from
spatial fluctuations in the inflaton decay rate which are due to quantum
fluctuations of light moduli fields coupling to the inflaton. We point out that
non-renormalizable operators, which lift the flatness of the moduli potential,
play an im... | 0304187v1 |
2003-05-06 | Depletion of small dust grains in the early stages of molecule formation | ISOCAM allowed the observation of diffuse interstellar regions where the
transition from atomic to molecular gas takes place. In this contribution we
report on spectacular variations of small dust grains abundance in such regions
observed with ISOCAM. In the four cirrus-like clouds observed, we note a
systematic disapp... | 0305084v1 |
2003-05-07 | Constraining the curvaton scenario | We analyse the curvaton scenario in the context of supersymmetry.
Supersymmetric theories contain many scalars, and therefore many curvaton
candidates. To obtain a scale invariant perturbation spectrum, the curvaton
mass should be small during inflation $m \ll H$. This can be achieved by
invoking symmetries, which supp... | 0305101v2 |
2003-05-18 | Bulk viscosity of strange quark matter in density-dependent quark mass model and dissipation of r-modes in strange stars | We study the bulk viscosity of strange quark matter(SQM) in density dependent
quark mass model(DDQM) under the background of self-consistent thermodynamics.
The correct formulae, with which the viscosity can be evaluated, are derived.
We also find that the viscosity in DDQM can be higher by 2 to 3 orders of
magnitude t... | 0305320v1 |
2004-11-02 | Spurious contribution to CR scattering calculations | The quasilinear theory for cosmic ray propagation is a well known and widely
accepted theory. In this paper, we discuss the different contributions to the
pitch-angle Fokker-Planck coefficient from large and small scales for slab
geometry using the damping model of dynamical turbulence. These examinations
will give us ... | 0411074v1 |
2005-06-07 | Resonant absorption in dissipative flux tubes | We study the resonant absorption of MHD waves in magnetized flux tubes with a
radial density inhomogeneity. Within the approximation that resistive and
viscous processes are operative in thin layers surrounding the singularities of
the MHD equations, we give the full spectrum of the eigenfrequencies and
damping rates o... | 0506141v3 |
2005-06-28 | Probing the interior of neutron stars with gravitational waves | We show here how the internal structure of a neutron star can be inferred
from its gravitational wave spectrum. Under the premise that the frequencies
and damping rates of a few $w$-mode oscillations are found, we apply an
inversion scheme to determine its mass, radius and density distribution. In
addition, accurate eq... | 0506681v1 |
2005-07-30 | The Largest Scale We Can Detect in the Universe and the Inflation | From the damping of the Cosmic Microwave Background Radiation
(CMB) anisotropy power spectrum at large scale and the recent accelerating
expansion of the Universe, we find that, there may be a largest scale which we
can detect in the Universe. From this, we can get the inflation parameters as
spectrum index $n_s$, e-... | 0508008v3 |
2005-12-15 | Galaxy Formation | I summarize current knowledge of galaxy formation with emphasis on the
initial conditions provided by the Lambda CDM cosmology, integral constraints
from cosmological quantities, and the demographics of high-redshift
protogalaxies. Tables are provided summarizing the number density, star
formation rate and stellar mass... | 0512384v1 |
2006-01-16 | Bistability in Interstellar Gas-Phase Chemistry | We present an analysis of "bistability" in gas-phase chemical models of dark
interstellar clouds. We identify the chemical mechanisms that allow high- and
low-ionization solutions to the chemical rate-equations to coexist. We derive
simple analytic scaling relations for the gas densities and ionization rates
for which ... | 0601323v1 |
2006-01-25 | Primordial magnetic fields and CMB anisotropies | Possible signatures of primordial magnetic fields on the Cosmic Microwave
Background (CMB) temperature and polarization anisotropies are reviewed. The
signals that could be searched for include excess temperature anisotropies
particularly at small angular scales below the Silk damping scale, B-mode
polarization, and no... | 0601570v1 |
2006-09-01 | Implication of Existence of Hybrid stars and Theoretical Expectation of Submillisecond Pulsars | We derive the bulk viscous damping timescale of hybrid stars, neutron stars
with quark matter core. The r-mode instability windows of the stars show that
the theoretical results are consistent with the rapid rotation pulsar data,
which may give an indication for the existence of quark matter in the interior
of neutron ... | 0609011v2 |
2006-11-07 | Viscosity in X-ray clusters: Braginskii over 5 | We argue that it is currently impossible to simulate X-ray clusters using
correct equations, because even the MHD description is not applicable. But
since fluid simulations actually reproduce observations quite well, one may try
to improve the fluid codes by including molecular transport of heat and
momentum. We calcul... | 0611243v1 |
2006-11-29 | Cosmological constraints on Neutrino - Dark Matter interactions | I summarize the results of a recent analysis where the cosmological effects
of interactions of neutrinos with cold Dark Matter (DM) is investigated. This
interaction produces diffusion-damped oscillations in the matter power
spectrum, analogous to the acoustic oscillations in the baryon-photon fluid. I
discuss the boun... | 0611887v1 |
2006-12-20 | Oscillations and Waves in coronal loops | In the past few years observations by high-resolution space imaging
telescopes and spectrometers have confirmed that a great variety of MHD waves
are supported in the solar corona of a low-beta plasma and fine structure. MHD
waves are an important diagnostic tool for the determination of the physical
parameters of coro... | 0612605v1 |
1994-06-26 | Symplectic Calculation of Lyapunov Exponents | The Lyapunov exponents of a chaotic system quantify the exponential
divergence of initially nearby trajectories. For Hamiltonian systems the
exponents are related to the eigenvalues of a symplectic matrix. We make use of
this fact to develop a new method for the calculation of Lyapunov exponents of
such systems. Our ap... | 9406010v1 |
1994-12-17 | When are vector fields Hamiltonian? | Dynamical systems can be quantised only if they are Hamiltonian. This prompts
the question from which our talk gets its title. We show how the simple
predator-prey equation and the damped harmonic oscillator can be considered to
be Hamiltonian with respect to an infinite number of non-standard Poisson
brackets. This ra... | 9412010v1 |
1996-07-14 | Statistical Description of Acoustic Turbulence | We develop expressions for the nonlinear wave damping and frequency
correction of a field of random, spatially homogeneous, acoustic waves. The
implications for the nature of the equilibrium spectral energy distribution are
discussed | 9607007v1 |
1996-12-09 | Chaotic hysteresis in an adiabatically oscillating double well | We consider the motion of a damped particle in a potential oscillating slowly
between a simple and a double well. The system displays hysteresis effects
which can be of periodic or chaotic type. We explain this behaviour by
computing an analytic expression of a Poincar'e map. | 9612015v1 |
1998-04-23 | Adiabatic geometric phases and response functions | Treating a many-body Fermi system in terms of a single particle in a
deforming mean field. We relate adiabatic geometric phase to susceptibility for
the noncyclic case, and to its derivative for the cyclic case. Employing the
semiclassical expression of susceptibility, the expression for geometric phase
for chaotic qua... | 9804037v1 |
1999-05-14 | Noise-induced flow in quasigeostrophic turbulence with bottom friction | Randomly-forced fluid flow in the presence of scale-unselective dissipation
develops mean currents following topographic contours. Known mechanisms based
on the scale-selective action of damping processes are not at work in this
situation. Coarse-graining reveals that the phenomenon is a kind of
noise-rectification mec... | 9905022v1 |
1999-07-30 | Free Decay of Turbulence and Breakdown of Self-Similarity | It has been generally assumed, since the work of von Karman and Howarth in
1938, that free decay of fully-developed turbulence is self-similar. We present
here a simple phenomenological model of the decay of 3D incompressible
turbulence, which predicts breakdown of self-similarity for low-wavenumber
spectral exponents ... | 9908006v1 |
1992-12-25 | Spatial Correlation of Conduction Electrons in Metal with Complicated Geometry Of The Fermi Surface | The "density-density" correlation function of conduction electrons in metal
is investigated. It is shown, that the asymptotic behaviour of the CF depends
on the shape and the local geometry of the Fermi surface. In particular, the
exponent of power law which describes the damping of Friedel oscillations at
large r (-4 ... | 9212032v1 |
1993-10-13 | Magneto-Optics of type-II superconductors | The magneto-optical activity of superconducting ${\rm YBa}_{2}{\rm
Cu}_{3}{\rm O}_{7}$ observed by Karrai {\it et al.} is not present in many
commonly employed models of vortex dynamics. Here we propose a simple, unifying
picture for the frequency dependent magneto-optic response of type-II
superconductors at low tempe... | 9310026v1 |
1993-12-02 | Theory of the Eigler-swith | We suggest a simple model to describe the reversible field-induced transfer
of a single Xe-atom in a scanning tunneling microscope, --- the Eigler-switch.
The inelasticly tunneling electrons give rise to fluctuating forces on and
damping of the Xe-atom resulting in an effective current dependent temperature.
The rate o... | 9312008v1 |
1994-07-25 | Diffusion Processes and Coherent States | It is shown that stochastic processes of diffusion type possess, in all
generality, a structure of uncertainty relations and of coherent and squeezed
states. This fact is used to obtain, via Nelson stochastic formulation of
quantum mechanics, the harmonic-oscillator coherent and squeezed states. The
method allows to de... | 9407100v1 |
1994-11-01 | Cyclotron resonance lineshape in a Wigner crystal | The cyclotron resonance absorption spectrum in a Wigner crystal is
calculated. Effects of spin-splitting are modelled by substitutional disorder,
and calculated in the coherent potential approximation. Due to the increasing
strength of the dipole-dipole interaction, the results show a crossover from a
double-peak spect... | 9411003v2 |
1995-01-23 | de Haas-van Alphen Oscillations in a Superconducting State at High Magnetic Fields | Low-temperature quantum oscillations of the dHvA amplitude are shown to
persist far below the upper critical field of a strongly type-II
superconductor, due to the gapless nature of the BCS quasiparticle spectrum in
high fields. The dHvA amplitude in the superconducting state is smaller than
its normal state countpart ... | 9501109v1 |
1995-08-14 | Density-dependent phonoriton states in highly excited semiconductors | The dynamical aspects of the phonoriton state in highly-photoexcited
semiconductors is studied theoretically. The effect of the exciton-exciton
interaction and nonbosonic character of high-density excitons are taken into
account. Using Green's function method and within the Random Phase
Approximation it is shown that t... | 9508046v1 |
1995-12-21 | Collective Modes in a Symmetry-Broken Phase: Antiferromagnetically Correlated Quantum Wells | We investigate the intersubband spin-density-excitation spectrum of a double
quantum well in a low-density symmetry-broken phase with interwell
antiferromagnetic correlations. This spectrum is related to the intensity
measured in depolarized inelastic light scattering (ILS) experiments and
therefore provides a means of... | 9512145v1 |
1996-03-15 | Boson-fermion model beyond mean-field approximation | A model of hybridized bosons and fermions is studied beyond the mean field
approximation. The divergent boson self-energy at zero temperature makes the
Cooper pairing of fermions impossible.The frequency and momentum dependence of
the self- energy and the condensation temperature $T_{c}$ of initially
localized bosons a... | 9603111v1 |
1996-05-15 | Internal Excitations and Dissipative Damping of Quantum Hall Skyrmions | We propose an intrinsic maximum speed for dissipationless E cross B drift of
Skyrmion quasiparticles in quantum Hall ferromagnets. When this speed is
exceeded, Skyrmions can radiate spin-waves by making internal excitations which
allow total spin to be conserved. Our proposal is illustrated by a
time-dependent Hartree-... | 9605091v1 |
1996-07-19 | Spectral properties of the planar t-J model | The single-particle spectral functions $A({\bf k},\omega)$ and self-energies
$\Sigma({\bf k},\omega)$ are calculated within the $t-J$ model using the
finite-temperature Lanczos method for small systems. A remarkable asymmetry
between the electron and hole part is found. The hole (photoemission) spectra
are overdamped, ... | 9607140v1 |
1996-11-19 | Quasi-particle behavior of composite fermions in the half-filled Landau level | We calculate the effect of infrared fluctuations of the Chern-Simons gauge
field on the single-particle Green's function of composite fermions in the
half-filled Landau level via higher-dimensional bosonization on a curved Fermi
surface. We find that composite fermions remain well-defined quasi-particles,
with an effec... | 9611139v2 |
1996-11-22 | Flux Noise near the Berezinskii-Kosterlitz-Thouless Transition | We study the flux noise in Josephson junction arrays in the critical regime
above the Berezinskii-Kosterlitz-Thouless transition. In proximity coupled
arrays a local ohmic damping for the phases is relevant, giving rise to
anomalous vortex diffusion and a dynamic scaling of the flux noise in the
critical region. It sho... | 9611177v2 |
1996-11-29 | Electron Green's Function in the Planar t-J Model | The electron Green's functions $G({\bf k},\omega)$ within the t-J model and
in the regime of intermediate doping is studied analytically using equations of
motion for projected fermionic operators and the decoupling of the self energy
into the single-particle and spin fluctuations. It is shown that the assumption
of ma... | 9612002v1 |
1997-02-21 | One-Particle Excitation of the Two-Dimensional Hubbard Model | The real part of the self-energy of interacting two-dimensional electrons has
been calculated in the t-matrix approximation. It is shown that the forward
scattering results in an anomalous term leading to the vanishing
renormalization factor of the one-particle Green function, which is a
non-perturbative effect of the ... | 9702200v1 |
1997-05-03 | Free induction signal from biexcitons and bound excitons | A theory of the free induction signal from biexcitons and bound excitons is
presented. The simultaneous existence of the exciton continuum and a bound
state is shown to result in a new type of time dependence of the free
induction. The optically detected signal increases in time and oscillates with
increasing amplitude... | 9705024v1 |
1997-06-06 | Dynamics of viscous amphiphilic films supported by elastic solid substrates | The dynamics of amphiphilic films deposited on a solid surface is analyzed
for the case when shear oscillations of the solid surface are excited. The two
cases of surface- and bulk shear waves are studied with film exposed to gas or
to a liquid. By solving the corresponding dispersion equation and the wave
equation whi... | 9706058v1 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.