共查询到20条相似文献，搜索用时 31 毫秒
1.
Ｓｙｎｃｈｒｏ－ＣｕｒｖａｔｕｒｅＲａｄｉａｔｉｏｎ──弯曲磁场中一种新的、更普遍的辐射张家铝（中国科技大学天体物理中心合肥２３００２６）郑广生（香港大学物理系）关键词同步辐射，曲率辐射，脉冲星磁层在脉冲星的辐射模型中，同步辐射和曲率辐射占有极其重要... 相似文献
2.
We investigate the acceleration and simultaneous radiative losses of electrons in the vicinity of relativistic shocks. Particles undergo pitch angle diffusion, gaining energy as they cross the shock by the Fermi mechanism and also emitting synchrotron radiation in the ambient magnetic field. A semi-analytic approach is developed which allows us to consider the behaviour of the shape of the spectral cut-off and the variation of that cut-off with the particle pitch angle. The implications for the synchrotron emission of relativistic jets, such as those in gamma-ray burst sources and blazars, are discussed. 相似文献
3.
Unified classical and quantum radiation mechanism for ultrarelativistic electrons in curved and inhomogeneous magnetic fields 总被引：1，自引：0，他引：1
We analyse the general radiation emission mechanism from a charged particle moving in a curved inhomogeneous magnetic field. The consideration of the gradient makes the vacuum magnetic field compatible with the Maxwell equations, and adds a non-trivial term to the transverse drift velocity, and, consequently, to the general radiation spectrum. To obtain the radiation spectrum in the classical domain a general expression for the spectral distribution and characteristic frequency of an electron in arbitrary motion is derived, by using Schwinger's method. The radiation patterns of the ultrarelativistic electron are represented in terms of the acceleration of the particle. The same results can be obtained by considering that the motion of the electron can be formally described as an evolution caused by magnetic and electric forces. By defining an effective electromagnetic field, which combines the magnetic field with the fictitious electric field associated to the curvature and drift motion, one can obtain all the physical characteristics of the radiation by replacing the constant magnetic field with the effective field. The power, angular distribution and spectral distribution of all three components (synchrotron, curvature and gradient) of the radiation are considered, in both the classical and the quantum domain, within the framework of this unified formalism. In the quantum domain the proposed approach allows the study of the effects of the inhomogeneities and curvature of the magnetic field on the radiative transition rates of electrons between low-lying Landau levels and the ground state. 相似文献
4.
The electron cyclotron resonance leads to a large enhancement of radiative force and may result in the ejection from magnetized compact stars (Papers I and II). On this ground, the acceleration of charged particles by radiation in a strong magnetic field is considered. Different regimes of ejection, the dependence on intensity, spectrum, angular distribution and polarization of accelerating radiation, and the influence of the opacity of ejecting plasma are analyzed. The energy of ejected plasma is shown to increase up to relativistic values, in many cases the gamma-factor appears to be 1. A possible connection of relativistic ejection with the origin of gamma-ray bursts and other astrophysical consequences are discussed. 相似文献
5.
The curvature radiation of charged relativistic particles in a dipole magnetic field is considered, taking into account the possibility that the emitted particles may reabsorb radiation. The calculations were carried out for emanating particles with both monoenergetic and power energy spectra. The dependence of the curvature radiation flow on both the frequency and angle between the magnetic axis and the line of sight is determined. The calculated results will be used in the second part of the paper to interprete the observable data on pulsars. 相似文献
6.
We use moment formalism of relativistic radiation hydrodynamics to obtain equations of motion of radial jets and solve them using polytropic equation of state of the relativistic gas. We consider curved space-time around black holes and obtain jets with moderately relativistic terminal speeds. In addition, the radiation field from the accretion disc, is able to induce internal shocks in the jet close to the horizon. Under combined effect of thermal as well as radiative driving, terminal speeds up to 0.75 (units of light speed) are obtained. 相似文献
7.
Jiong Liu Ye-Fei Yuan Xiao-Long Deng Center for Astrophysics University of Science Technology of China Hefei 《中国天文和天体物理学报》2007,7(2):304-316
Synchro-curvature radiation describes the emission from a relativistic charged par- ticle which is moving and spiralling in a curved magnetic field. We investigate the maser emission for synchro-curvature radiation including drift of the guiding center of the radiating electron. It is shown that under some conditions the absorption coefficient can be negative, so maser can happen. These conditions are different from those needed for maser emission of curvature radiation including drift of the charged particles. We point out that our results, in- cluding the emissivity, can reduce to these of curvature radiation. Previously it was found that synchro-curvature radiation can not generate maser in vacuum, but we argue that synchro- curvature radiation including drift can generate maser even in vacuum. We discuss the possi- bilities of the potential applications of the synchro-curvature maser in modeling gamma ray bursts and pulsars. 相似文献
8.
The average energy radiation rate is calculated exactly for the case of a charged particle injected with arbitrary momentum into an intense electromagnetic field which is propagating along a uniform magnetostatic field. The treatment is relativistic. 相似文献
9.
Myeong-Gu Park 《Monthly notices of the Royal Astronomical Society》2006,367(4):1739-1745
Radiation interacts with matter via exchange of energy and momentum. When matter is moving with a relativistic velocity or when the background space–time is strongly curved, rigorous relativistic treatment of hydrodynamics and radiative transfer is required. Here, we derive fully general relativistic radiation hydrodynamic equations from a covariant tensor formalism. The equations can be applied to any three-dimensional problems and are rather straightforward to understand compared to the comoving frame-based equations. The current approach is applicable to any space–time or coordinates, but in this work we specifically choose the Schwarzschild space–time to show explicitly how the hydrodynamic and the radiation moment equations are derived. Some important aspects of relativistic radiation hydrodynamics and the difficulty with the radiation moment formalism are discussed as well. 相似文献
10.
We generalize the hot relativistic MHD wind analysis to include the anisotropy of the pressure created in the pulsar wind by the strong magnetic field. Even with anisotropy the relativistic MHD equations integrate. In a very intense magnetic field, the motion of relativistic particles becomes rapidly one-dimensional in the direction of the field due to the very important radiative losses. Consequently, their distribution function becomes also one-dimensional and the component of the pressure, in the direction perpendicular to the magnetic field, decrease. In the limitP ⊥?0,P ∥≠0 we obtain a solution for the fluid flow which, starting at the neutron star surface, reaches smoothly infinity. 相似文献
11.
Induced Compton scattering by independent relativistic particles in a radiation field is considered from both quantum mechanical and classical viewpoints. Quantum mechanically, the particle recoil causes an imperfect cancellation of the induced scattering rates between pairs of photon states. This results in a net energy transfer from the radiation field to the particle. Classically, the electrodynamical effects are manifestations of non-linear coupling between different wave amplitudes in the equation of motion. The results from these two approaches are related and shown to be equivalent. 相似文献
12.
Evgeny V. Derishev 《Astrophysics and Space Science》2007,309(1-4):157-161
We consider the synchrotron emission from relativistic shocks assuming that the radiating electrons cool rapidly (either through
synchrotron or any other radiation mechanism). It is shown that the theory of synchrotron emission in the fast cooling regime
can account for a wide range of spectral shapes. In particular, the magnetic field, which decays behind the shock front, brings
enough flexibility to the theory to explain the majority of gamma-ray burst spectra even in the parameter-free fast cooling
regime. Also, we discuss whether location of the peak in observed spectral energy distributions of gamma-ray bursts and active
galactic nuclei can be made consistent with predictions of diffusive shock acceleration theory, and find that the answer is
negative. This result is a strong indication that a particle injection mechanism, other than the standard shock acceleration,
works in relativistic shocks. 相似文献
13.
The effect of a strong magnetic field on neutron stars or white dwarfs is calculated for Thomson scattering in a strong magnetic field with radiation damping. The Stokes's parameters for the scattered radiation are computed explicitly in terms of the state of polarization of the incident wave, the electrocyclotron frequency, the angle of incidence, and the angle of scattering. The criterion for the magnetic field to substantially affect the Stokes's parameters is that the photon frequency be less than the electrocyclotron frequency. The effects of classical radiation damping are explicitly taken into account by using the Abraham-Lorentz equation. The corresponding quantum mechanical treatment for Compton scattering in a relativistic electron gas is now under investigation. 相似文献
14.
The propagation of weak waves has been studied by taking into account the influence of thermal radiative field. The singular surface theory is used to determine the modes of wave propagation and to evaluate the behaviour at the wave head. The effects of thermal radiation, conduction and the initial wave front curvature on the nonlinear breaking of weak waves are discussed. It is concluded that, under the thermal radiation effects, the shock wave formation is either disallowed or delayed. On the other hand, the thermal conduction effects destabilize the waves. 相似文献
15.
I. M. Chertok V. V. Fomichev R. V. Gorgutsa A. K. Markeev T. S. Podstrigach H. Aurass J. Hildebrandt B. Kliem A. Krüger J. Kurths M. KarlickýA A. Tlamicha H. W. Urbarz P. Zlobec 《Astronomische Nachrichten》1990,311(1):55-62
Basing on radio measurements from different stations the paper presents a compilation of observations and resultinng questions concerning the interpretation of some remarkable features of the solar behind-limb event on 16th February 1984. The event was related to a very strong relativistic particle emission. Attention is paid to the related microwave radiation stimulating a discussion of the discrimination between plasma and gyromagnetic radiation being important for plasma diagnostics. Another outstanding feature is the occurrence of a spectacular multi-band U-shaped type II burst pattern challenging a discussion of possible higher harmonic plasma radiation. 相似文献
16.
The growth of weak MHD discontinuities have been studied in a radiation induced flow field at very high temperature. Growth and decay properties of weak MHD discontinuities have been discussed under the influences of time-dependent gasdynamic field, the radiation field and the magnetic field with finite electrical conductivity. The effects of thermal radiation and conduction of the global behaviour of weak MHD discontinuities have been studied under a quasi-equilibrium and quasi-isotropic hypothesis of the differential approximation to the radiative heat transfer equation. It is shown that the existence of the time-dependent radiation field gives rise to a radiation induced wave which has a negligibly small effect on the non-relativistic flow properties of the gasdynamic field. It is also shown that the radiation stresses resist the steepening tendency of a compressive weak wave and help in stabilizing it whereas the thermal conduction effects counteracts to destabilize it. It is found that under radiation effects the shock formation is either disallowed or delayed. The two cases of diverging waves and converging waves have been studied separately to answer a particular question as to when a shock discontinuity or a coustic will be formed or disallowed under curvature effects. 相似文献
17.
K.-I. Nishikawa C. B. Hededal P. E. Hardee G. J. Fishman C. Kouveliotou Y. Mizuno 《Astrophysics and Space Science》2007,307(1-3):319-323
We have applied numerical simulations and modeling to the particle acceleration, magnetic field generation, and emission from
relativistic shocks. We investigate the nonlinear stage of theWeibel instability and compare our simulations with the observed
gamma-ray burst emission. In collisionless shocks, plasma waves and their associated instabilities (e.g., the Weibel, Buneman
and other two-stream instabilities) are responsible for particle (electron, positron, and ion) acceleration and magnetic field
generation. 3-D relativistic electromagnetic particle (REMP) simulations with three different electron-positron jet velocity
distributions and also with an electron-ion plasma have been performed and show shock processes including spatial and temporal
evolution of shocks in unmagnetized ambient plasmas. The growth time and nonlinear saturation levels depend on the initial
jet parallel velocity distributions. Simulations show that the Weibel instability created in the collisionless shocks accelerates
jet and ambient particles both perpendicular and parallel to the jet propagation direction. The nonlinear fluctuation amplitude
of densities, currents, electric, and magnetic fields in the electron-positron shocks are larger for smaller jet Lorentz factor.
This comes from the fact that the growth time of the Weibel instability is proportional to the square of the jet Lorentz factor.
We have performed simulations with broad Lorentz factor distribution of jet electrons and positrons, which is assumed to be
created by photon annihilation. Simulation results with this broad distribution show that the Weibel instability is excited
continuously by the wide-range of jet Lorentz factor from lower to higher values. In all simulations the Weibel instability
is responsible for generating and amplifying magnetic fields perpendicular to the jet propagation direction, and contributes
to the electron’s (positron’s) transverse deflection behind the jet head. This small scale magnetic field structure contributes
to the generation of “jitter” radiation from deflected electrons (positrons), which is different from synchrotron radiation
in uniform magnetic fields. The jitter radiation resulting from small scale magnetic field structures may be important for
understanding the complex time structure and spectral evolution observed in gamma-ray bursts or other astrophysical sources
containing relativistic jets and relativistic collisionless shocks. The detailed studies of shock microscopic process evolution
may provide some insights into early and later GRB afterglows. 相似文献
18.
Peter D. Noerdlinger 《Astrophysics and Space Science》1971,13(1):70-73
The Poynting-Robertson formulae are used to evaluate the motion and terminal velocity of a particle ejected from rest in a powerful radiation field due to a point source, generalizing the results of Chandrasekhar (1934) to the relativistic case.Contributions from the Lick Obsrvatory, No. 335. 相似文献
19.
E. V. Derishev F. A. Aharonian V. V. Kocharovsky Vl. V. Kocharovsky 《Astrophysics and Space Science》2005,297(1-4):21-30
We discuss the properties of gamma-ray radiation accompanying the acceleration of cosmic rays via the converter mechanism.
The mechanism exploits multiple photon-induced conversions of high-energy particles from charged into neutral state (namely,
protons to neutrons and electrons to photons) and back. Because a particle in the neutral state can freely cross the magnetic
field lines, this allows to avoid both particle losses downstream and reduction in the energy gain factor, which normally
takes place due to highly collimated distribution of accelerated particles. The converter mechanism efficiently operates in
relativistic outflows under the conditions typical for Active Galactic Nuclei, Gamma-Ray Bursts, and microquasars, where it
outperforms the standard diffusive shock acceleration.
The accompanying radiation has a number of distinctive features, such as an increase of the maximum energy of synchrotron
photons and peculiar radiation beam-pattern, whose opening angle is much wider at larger photon energies. This provides an
opportunity to observe off-axis relativistic jets in GeV–TeV energy range. One of the implications is the possibility to explain
high-latitude unidentified EGRET sources as off-axis but otherwise typical relativistic-jet sources, such as blazars. 相似文献
20.
J. Klačka 《Earth, Moon, and Planets》1994,64(1):55-58
The action of the solar electromagnetic radiation (in the form of the Poynting-Robertson effect) on the motion of interplanetary dust particle in the gravitational field of the Sun is discussed from the theoretical point of view. Results are presented to all orders inv/c (c - speed of light,v -orbital velocity of the particle) - general relativistic formula is presented. 相似文献