DYNAMICS AND EMISSION OF MILDLY RELATIVISTIC PLASMA

2012 ◽  
Vol 12 ◽  
pp. 1-9
Author(s):  
A. G. AKSENOV ◽  
R. RUFFINI ◽  
I. A. SIUTSOU ◽  
G. V. VERESHCHAGIN
Keyword(s):  
Compton Scattering ◽  
Thermal Equilibrium ◽  
Nonequilibrium Plasma ◽  
Distribution Functions ◽  
Photon Pair ◽  
Accelerated Expansion ◽  
Spherically Symmetric ◽  
Two Photon ◽  
Electron Positron ◽  
Pair Annihilation

Initially optically thick (with τ = 3⋅107) spherically symmetric outflow consisting of electron-positron pairs and photons is considered. We do not assume thermal equilibrium, and include the two-body processes that occur in such plasma: Möller and Bhabha scattering of pairs, Compton scattering, two-photon pair annihilation, two-photon pair production, together with their radiative three-body variants: bremsstrahlung, double Compton scattering, and three-photon pair annihilation, with their inverse processes. We solve numerically the relativistic Boltzmann equations in spherically symmetric case for distribution functions of pairs and photons. Three epochs are considered in details: a) the thermalization, which brings initially nonequilibrium plasma to thermal equilibrium; b) the self-accelerated expansion, which we find in agreement with previous hydrodynamic studies and c) decoupling of photons from the expanding electron-positron plasma. Photon spectra are computed, and appear to be non thermal near the peak of the luminosity. In particular, the low energy part of the spectrum contain more power with respect to the black body one.

scholarly journals Compton Scattering, Pair Annihilation, and Pair Production in a Plasma

2000 ◽  
Vol 195 ◽  
pp. 359-366
Author(s):  
V. Krishan
Keyword(s):  
Compton Scattering ◽  
Cross Sections ◽  
High Plasma ◽  
Electron Positron ◽  
Pair Annihilation ◽  
The Cross ◽  
Unmagnetized Plasma ◽  
Electron Photon ◽  
Electron Positron Pair ◽  
Photon Coupling

The square of the four-momentum of a photon in vacuum is zero. However, in an unmagnetized plasma, it is equal to the square of the plasma frequency. Further, the electron-photon coupling vertex is modified in a plasma to include the effect of the plasma medium. I calculate the cross sections of three processes in a plasma—Compton scattering and electron-positron pair annihilation and production. At high plasma densities, the cross sections are found to change significantly. Such high plasma densities exist in several astrophysical sources.

scholarly journals Quantum Electrodynamics in Strong Magnetic Fields. III. Electron?Photon Interactions

1983 ◽  
Vol 36 (6) ◽  
pp. 799 ◽  
Author(s):  
DB Melrose ◽  
AJ Parle
Keyword(s):  
Compton Scattering ◽  
Ground State ◽  
Quantum Electrodynamics ◽  
Relativistic Quantum ◽  
Photon Pair ◽  
Photon Excitation ◽  
Pair Annihilation ◽  
Quantum Electron ◽  
Electron Photon ◽  
Photon Interactions

A version of QED is developed which allows one to treat electron-photon interactions in the magnetized vacuum exactly and which allows one to calculate the responses of a relativistic quantum electron gas and include these responses in QED. Gyromagnetic emission and related crossed processes, and Compton scattering and related processes are discussed in some detail. Existing results are corrected or generalized for nonrelativistic (quantum) gyroemission, one-photon pair creation, Compton scattering by electrons in the ground state and two-photon excitation to the first Landau level from the ground state. We also comment on maser action in one-photon pair annihilation.

scholarly journals Strong spin squeezing induced by weak squeezing of light inside a cavity

Nanophotonics ◽  
2020 ◽  
Vol 9 (16) ◽  
pp. 4853-4868
Author(s):  
Wei Qin ◽  
Ye-Hong Chen ◽  
Xin Wang ◽  
Adam Miranowicz ◽  
Franco Nori
Keyword(s):  
Spin Squeezing ◽  
Nitrogen Vacancy ◽  
Photon Pair ◽  
Cavity Resonance ◽  
Alternative Mechanism ◽  
Simple Method ◽  
Two Photon ◽  
Electronic Spin ◽  
Anti Stokes ◽  
Strong Spin

AbstractWe propose a simple method for generating spin squeezing of atomic ensembles in a Floquet cavity subject to a weak, detuned two-photon driving. We demonstrate that the weak squeezing of light inside the cavity can, counterintuitively, induce strong spin squeezing. This is achieved by exploiting the anti-Stokes scattering process of a photon pair interacting with an atom. Specifically, one photon of the photon pair is scattered into the cavity resonance by absorbing partially the energy of the other photon whose remaining energy excites the atom. The scattering, combined with a Floquet sideband, provides an alternative mechanism to implement Heisenberg-limited spin squeezing. Our proposal does not need multiple classical and cavity-photon drivings applied to atoms in ensembles, and therefore its experimental feasibility is greatly improved compared to other cavity-based schemes. As an example, we demonstrate a possible implementation with a superconducting resonator coupled to a nitrogen-vacancy electronic-spin ensemble.

scholarly journals Radial Velocity Profiles for Anisotropic Spherically Symmetric Clusters: An Example

1988 ◽  
Vol 126 ◽  
pp. 691-692
Author(s):  
Herwig Dejonghe
Keyword(s):  
Distribution Function ◽  
Radial Velocity ◽  
Velocity Dispersion ◽  
Mass Density ◽  
Distribution Functions ◽  
Spherically Symmetric ◽  
Line Profiles ◽  
Anisotropic Models ◽  
The Family

A 1-parameter family of anisotropic models is presented. They all satisfy the Plummer law in the mass density, but have different velocity dispersions. Moreover, the stars are not confined to a particular subset of the total accessible phase space. This family is mathematically simple enough to be explored analytically in detail. The family is rich enough though to allow for a 3-parameter generalization which illustrates that even when both the mass density and the velocity dispersion profiles are required to be the same, a degeneracy in the possible distribution functions persists. The observational consequences of the degeneracy can be studied by calculating the observable radial velocity line profiles obtained with different distribution functions. It turns out that line profiles are relatively sensitive to changes in the distribution function. They therefore can be considered to be more natural observables when a determination of the distribution function is desired.

scholarly journals Pair Production in AGN

1989 ◽  
Vol 134 ◽  
pp. 194-196
Author(s):  
C. Done ◽  
A. C. Fabian
Keyword(s):  
Pair Production ◽  
Compton Scattering ◽  
Energy Flux ◽  
Large Fraction ◽  
Small Region ◽  
X Rays ◽  
X Ray ◽  
Electron Positron ◽  
Γ Rays ◽  
Radiant Power

The X-ray luminosity and variability of many AGN are sufficiently extreme that any hard γ-rays produced in the source will collide with the X-rays and create electron-positron pairs, rather than escape. A small region where vast amounts of energy are produced, such as an AGN, is an ideal place to accelerate particles to relativistic energies and so produce γ-rays by Compton scattering. The observed X-ray spectra of AGN are hard and indicate that most of the luminosity is at the highest energies so that absorption of the γ-rays represents a large fraction of the energy flux, which can then be re-radiated at lower energies. Pairs can thus effectively reprocess much of the radiant power in an AGN.

MOMENTUM DISTRIBUTION OF METALLIC ELECTRONS BY POSITRON ANNIHILATION

1957 ◽  
Vol 35 (2) ◽  
pp. 168-183 ◽  
Author(s):  
A. T. Stewart
Keyword(s):  
Positron Annihilation ◽  
Momentum Distribution ◽  
Center Of Mass ◽  
Velocity Dependence ◽  
Conduction Electrons ◽  
Two Photon ◽  
Photon Decay ◽  
Electron Positron ◽  
Momentum Distributions ◽  
Annihilation Probability

The angular correlation of photons from the two-photon decay of positrons has been measured for positrons annihilating in some 34 elements, mostly metals. These data give the momentum distribution of photons and hence of the center of mass of the annihilating electron–positron pairs. The momentum distributions are discussed in terms of the velocity dependence of the annihilation probability. It is concluded that the observed momentum distributions are primarily the momentum distributions of the conduction electrons in the metals. A higher momentum component is observed, which is attributed to ion core effects.

Sign in / Sign up

Export Citation Format

Share Document