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1.
A finite amplitude linearly polarized electromagnetic wave propagating in a relativistic plasma, is found to generate the longitudinal d.c. as well as the oscillating electric field at the second harmonic. In a plasma consisting of only electrons and positrons, these fields cannot be generated.The evolution of the electromagnetic waves is governed by the non-linear Schrödinger equation which shows that the electromagnetic solitons are always possible in ultra-relativistic plasmas (electron-ion or electron-positron) but in a plasma with relativistic electrons and nonrelativistic ions, these solitons exist only if 1(KT e/meC2)<(2m i/15me);m e andm i being the electron and ion mass andT e the electron temperature. Both the d.c. electric field and the solitons provide a nonlinear mechanism for anomalous acceleration of the particles. This model has direct relevance to some plasma processes occurring in pulsars.  相似文献   

2.
A non-linear Schrödinger equation which characterizes the non-linear electrostatic waves in collisionless turbulent plasma is derived. Detailed analysis of this equation for the non-linear Langmuir waves is presented to show how the ion dynamics affects the envelope behaviour of these waves. Necessary condition for the existence of Langmuir envelope solitons is found to bek 2 D 2 (m/M);k being the characteristic wave number, D the electron Debye length andm andM the electron and the proton mass.Paper dedicated to Professor Hannes Alfvén on the occasion of his 70th birthday, 30 May, 1978.  相似文献   

3.
The field-to-particle method of H. P. Robertson as applied by Noonan, in order to obtain the general relativistic equations describing the trajectory of a photon in a refractive medium, is compared with Synge’s general relativistic Hamiltonian theory of waves and rays. For a photon in vacuum it is known that both approaches yield the same equation for the trajectory, i.e., a null geodesic. However for a photon in a medium, in contradistinction to the Hamiltonian theory, the field-to-particle method (a) yields equations of the photon trajectory valid only in a nondispersive medium, (b) the time component u0 of the tangent to the ray remains an undetermined quantity, (c) agreement with the Hamiltonian theory is achieved by substituting into Noonan’s equations the Hamiltonian expression for u 0. Published in Astrofizika, Vol. 42, No. 3, pp. 449–455, July–September, 1999.  相似文献   

4.
The Machian models of isotropic expanding universes according to the “inertia-free” gravo-dynamics imply the equations between the instantan values H0 and q0 of the HUBBLE parameter H, the acceleration q, and the matter density o. Therefore, in Machian universes with linear expansion q0 = 0 the energy integral E = -1/2ϵc2 is zero and the matter density becomes (with H02R02 = c2/3) (f0 the Newtonian gravitational constant). This is the critical density in general relativistic cosmology.  相似文献   

5.
We discuss results from a decade long program to study the fine-scale structure and the kinematics of relativistic AGN jets with the aim of better understanding the acceleration and collimation of the relativistic plasma forming AGN jets. From the observed distribution of brightness temperature, apparent velocity, flux density, time variability, and apparent luminosity, the intrinsic properties of the jets including Lorentz factor, luminosity, orientation, and brightness temperature are discussed. Special attention is given to the jet in M87, which has been studied over a wide range of wavelengths and which, due to its proximity, is observed with excellent spatial resolution. Most radio jets appear quite linear, but we also observe curved non-linear jets and non-radial motions. Sometimes, different features in a given jet appear to follow the same curved path but there is evidence for ballistic trajectories as well. The data are best fit with a distribution of Lorentz factors extending up to γ∼30 and intrinsic luminosity up to ∼1026 W Hz−1. In general, gamma-ray quasars may have somewhat larger Lorentz factors than non gamma-ray quasars. Initially the observed brightness temperature near the base of the jet extend up to ∼5×1013 K which is well in excess of the inverse Compton limit and corresponds to a large excess of particle energy over magnetic energy. However, more typically, the observed brightness temperatures are ∼2×1011 K, i.e., closer to equipartition.  相似文献   

6.
Parameteric instabilities in the relativistic plasma are considered. It is shown that in the electron relativistic plasma (T em 0e c 2) the electron mass oscillation in the external electrical field leads to the instability of Langmuir and low frequency aperiodic oscillations as well. In the case of the hot electron ion plasma with relativistic electron temperature the low frequency aperiodic and periodic oscillations are studied. The wave increments for all considered cases are obtained.  相似文献   

7.
The analysis of discrete radio sources spectra in the range 10–5000 MHz reveals that deviations from a power law in the low-frequency region may be due to distortion of differential energy spectra of relativistic electrons at low energies. An empirical expression for an energy-spectrum law was found to be in a good agreement with most of the radio spectra measured. The main physical parameters of 92 sources are evaluated. It is concluded that a low-energy electron excess exists with respect to the lawE – in most of the discrete sources which radiate non-linear low-frequency spectra.The forms of radio and energy spectra are further considered in a logarithmic scale.  相似文献   

8.
It has become clear in recent years that relativistic beaming is a good explanation for the BL Lac phenomenon. Of studies based on the relativistic beaming model of BL Lac objects, we note that the orientation of jet's axis to the line-of-sight is very small and, therefore, the observed flux emitted from a rapidly moving source is orders of magnitude higher than the flux in its rest-frame:F obs = 3 + F intr, where is the bulk relativistic Doppler factor. Then the observed apparent magnitudem v must be corrected for this effect. For our 39 samples, the corrected apparent magnitudem v corr and logZ have a good correlation.  相似文献   

9.
We discuss a new N-body simulation method for studying black hole binary dynamics. This method avoids previous numerical problems due to large mass ratios and trapped orbits with short periods. A treatment of relativistic effects is included when the associated time-scale becomes small. Preliminary results with up to N = 2.4 × 10 5 particles are obtained showing systematic eccentricity growth until the relativistic regime is reached, with subsequent coalescence in some cases. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

10.
We investigate static, spherical configurations of cold catalized matter in the Einstein-Cartan theory of gravitation. Assuming that density of spin is proportional to the number density of baryonsn and using an equation of state of a degenerate, relativistic Fermi gas, we numerically integrated the relativistic equation of equilibrium. We have also studied the stability of those configurations. Configurations with central number densityn c such that where is the effective pressure, are very similar to general relativistic configurations with the same central density. In the Einstein-Cartan theory there exists another disjoint family of equilibrium configurations for which but . Those configurations have very small masses 10–6 g and raddi 10–34 cm and are unstable.Supported in part by Research Grant MR-I-7.  相似文献   

11.
From July 13 to August 21, 1994, we observed Jupiter at 1420 MHz using one of the 30-m single dishes of the Instituto Argentino de Radioastronomía. After the impact of fragment G, we detected a rapid increase of the 21cm-continuum flux, which reached the maximum (≈ 20% of Jupiter's flux) at the end of the impact period. The nature of this radiation is clearly synchrotron. We interpret it in terms of a new population of relativistic electrons (≈ 2 × 1029) injected into the Jovian magnetosphere as a consequence of the impact explosions. The proposed mechanism is that the relativistic plasma was blown as magnetic clouds that flowed along the magnetic lines of force towards the jovimagnetic equator. We constructed a model in which the energies of the fresh electrons, generated within the magnetized clouds with a power law energy spectrum, were highly degraded by the comet dust grains attached to the magnetized plasma. The model can account for the spectral shape based on observations at several frequencies (de Pater et al., 1995, Science 268, 1879; Venturi et al., 1996, Astron. Astrophys. 316, 243). The energy released by the explosions under the form of relativistic electrons is of ≈ 2 × 1025 erg, which represents a fraction of about 1–3 per cent of the explosion energy. The efficiency in converting the explosion energy into the relativistic electron energy is, therefore, of the same order of magnitude as that of supernova explosions. An alternative model is considered. This gives figures for the total energy and number of relativistic electrons that are similar to the corresponding ones of the favoured model. Finally, we suggest that the behavior of the flux decay in the various observed frequencies is the result of the diffusion of electrons into the loss-cone due to the resonant scattering of the electrons by Alfven waves. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

12.
We address gravitation and inertia in the framework of a general gauge principle (GGP) which accounts for the gravitation gauge group G R generated by a hidden local internal symmetry implemented on the flat space. Following the method of phenomenological Lagrangians, we connect the group G R to a non-linear realization of the Lie group of the distortion G D of the local internal properties of six-dimensional flat space, M 6, which is assumed as a toy model underlying four-dimensional Minkowski space. We study the geometrical structure of the space of parameters and derive the Maurer–Cartan’s structure equations. We treat distortion fields as Goldstone fields, to which the metric and connection are related, and we infer the group invariants and calculate the conserved currents. The agreement between the proposed gravitational theory and available observational verifications is satisfactory. Unlike the GR, this theory is free of fictitious forces, which prompts us to address separately the inertia from a novel view point. We construct a relativistic field theory of inertia, which treats inertia as a distortion of local internal properties of flat space M 2 conducted under the distortion inertial fields. We derive the relativistic law of inertia (RLI) and calculate the inertial force acting on the photon in a gravitating system. In spite of the totally different and independent physical sources of gravitation and inertia, the RLI furnishes a justification for the introduction of the Principle of Equivalence. Particular attention is given to the realization of the group G R by the hidden local internal symmetry of the abelian group U loc=U(1) Y ×diag[SU(2)], implemented on the space M 6. This group has two generators, the third component T 3 of isospin and the hypercharge Y, implying Q d =T 3+Y/2, where Q d is the distortion charge operator assigning the number −1 to particles, but +1 to anti-particles. This entails two neutral gauge bosons that coupled to T 3 and Y. We address the rearrangement of the vacuum state in gravity resulting from these ideas. The neutral complex Higgs scalar breaks the vacuum symmetry leaving the gravitation subgroup intact. The resulting massive distortion field component may cause an additional change of properties of the spacetime continuum at huge energies above the threshold value.  相似文献   

13.
Second-step acceleration of nonrelativistic protons and ions in impulsive solar flares is discussed extending our earlier calculations for relativistic electrons. We derive the relevant particle transport equation, discussing in detail the influence of the particle's effective charge and mass number on the various momentum gain (stochastic acceleration, diffusive shock wave acceleration) and loss (Coulomb interactions, particle escape) processes. Analytical solutions for the ion-momentum spectra in the hard-sphere approximation are given. The inclusion of Coulomb losses modify the particle spectra significantly at kinetic energies smaller than E B = 0.64( e /5.0) MeV nucl.–1 from the well-known Bessel function variation in long-duration flares. For equal injection conditions this modification explains the observed much smaller ion fluxes from impulsive flares at high energies as compared to long-duration flares. We also calculate the 3He/4He-isotope variation as a function of momentum in impulsive flares in the hard-sphere approximation and find significant variations near E m = 0.38(T e /2 × 106 K) MeV nucl.–1, where T e is the electron temperature of the coronal medium.  相似文献   

14.
Detailed analyses by independent research groups over several decades reveal a significant discrepancy between the observed rate of periastron advance in the detached eclipsing binary star systems DI Herculis and V541 Cygni and the values theoretically predicted from the combined classical and general relativistic effects. A modification to Newton’s gravitational theory is proposed in this investigation to account for these discrepancies, and is represented by
F = - \fracGm1m2r3r - \fracGom1m2r2r\mathbf{F} = - \frac{Gm_{1}m_{2}}{r^{3}}\boldsymbol{r} - \frac{G_{o}m_{1}m_{2}}{r^{2}}\boldsymbol{r}  相似文献   

15.
We modify Walecka's mean field method by regarding the nucleons as point sources when considering the vector meson field and obtain a new softer equation of state. Applying the latter to the structural equations of neutron stars gives a maximum mass of 1.7 M⊙ amd a rotational inertia of 1.62 × 1045gcm2. in good agreement with observations. The use of our improved mean field method reduces considerably the differences in the mass and rotational inertia given by relativistic and non-relativistic calculations.  相似文献   

16.
In the present paper we consider the frequency spectrum, time variations and polarization of the flux of synchrotron radio emission from a source which consists of two components flying apart in opposite directions with relativistic velocities at the same time expanding. A comparison of the calculations with unusual double-humped spectra of some radio sources suggests the existence in their nuclei of such double components which are at an early stage of relativistic ejection. In particular the double-humped spectra of 3C 84 and 4C 50.11/NRAO-150 can be interpreted in the proposed model (see Figures 6, 7, 12 and Equations (22), (32)). In this model the ratio of maximum frequenciesv 1m/v 2m should be larger than that of the maximum fluxesF v1m (1)/F v2m (2).The linear polarization of the double-humped spectrum is analysed. It is found under rather specific conditions that at the low-frequency maximum of the spectrum of the type given in Figures 6 and 7 a lower degree of linear polarization is expected than at the high-frequency maximum. In addition, it is natural to expect the appearance of circular polarization in sources with internal largescale relativistic motions. The time variations of the radio flux of some QSS, N-galaxies, and nuclei of Seyfert galaxies can also be interpreted in the suggested model of two clouds of relativistic electrons flying apart in different directions with relativistic velocities while simultaneously expanding. For example, Figure 11 shows the flux variations at 3 frequencies whose ratio is 16:4:1. This picture is similar to the observations of 3C 279 at 3.4 mm, 2 cm and 6 cm, and several other sources (Kellermann andPauliny-Toth, 1968).There have been a number of attempts to explain the flux variations of radio sources in the model of successive, but unrelated outbursts of clouds of relativistic electrons caused by supernova explosions. This model meets many difficulties and seems improbable. In this paper we suggest experimental tests to make a final choice between the model of double components flying apart relativistically and the model of two successive, but unrelated, outbursts from supernovae.If the suggested model of explosions in radio sources is correct, then the processes of variable energy output in such different populations as QSS, N-galaxies, radio-galaxies and the nuclei of normal galaxies have a similar nature, differing only in quantity.Translated by D. F. Smith.  相似文献   

17.
A computation is presented that predicts with sufficient accuracy the energy transfer between relativistic electrons and radio photons by means of stimulated Compton events. It is shown that the majority of currently assumed parameters for quasi-stellar objects result in situations where the relativistic electrons must be producedinitially at rather high energies (102–103) in order to survive for any appreciable length of time.  相似文献   

18.
We discuss the implications of the Brans-Dicke scalar-tensor theory for cosmology with particular emphasis on the primordial element abundances that would obtain. Two general classes of models are found. Models of one class expand through the nuclear burning stage slightly more rapidly than the general relativistic case: models of the other class may expand at any rate whatsoever. The first class of models yeilds primordial abundances of D, He3 and He4 in agreement with their general relativistic values if the present mass density is low. High-density cosmologies, however, would produce too much He4. The second class of models yields element abundances which are far too high unless the expansion rate was quite large: in this case no He4 at all is produced. Finally, we determine the rate of change of the constant of gravitationG at the present epoch. For all but a very small class of models is negative at the present epoch. Models with positive values of at the present epoch produce no primordial He4 whatsoever, and have ages significantly lower than the corresponding general relativistic ages.  相似文献   

19.
Spherical-symmetric massive structures with a relativistic polytropic equation of state have been studied in detail. Thevarious static parameters have been calculated under all possible variations of 0 (=P 0/E 00 pertaining to the central value) and the polytropic indexn. In particular, the values of the static parameters have been identified under the extreme relativistic conditions and for the most bound structures. The structures have been used to model neutron stars and the various neutron parameters have been calculated. Radial pulsation and rotation of these configurations have also been discussed.  相似文献   

20.
We report here the results of our examination of the physical properties of Vaidya-Tikekar's model for a relativistic star. Full details will be published elsewhere. The analysis yields a strong indication that the model is stable with respect to infinitesimal radial oscillations. We find that the adiabatic speed of sound is smaller than the speed of light everywhere inside the fluid sphere if the radius of the sphere is larger than 1.46 times its Schwarzschild radius. We also find that the fluid must necessarily be supraluminal somewhere if the speed of sound is decreasing outwards close to the center. We further find that the strong energy condition is fulfilled everywhere if it is fulfilled at the center. Since the ratio of the pressure p and the density ⋅ is decreasing outwards, this indicates that the temperature gradient is negative. We also find that the relativistic adiabatic index is larger than two. Demanding the fluid to be causal, and taking the pressure and the density to be somewhere given by 7.4 ⋅ 1033 dynes/cm3 and 5.1 ⋅ 1014 g/cm3, we calculate the maximum mass of the fluid sphere to be 3 solar masses.  相似文献   

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