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1.
Yu. A. Rylov 《Astrophysics and Space Science》1984,107(2):381-401
A self-consistent pulsar magnetospheric model with electron-positron pair production is considered. Unlike conventional models, the primary particles (electrons) are accelerated towards the neutron star and their curvature radiation towards a star generates electron-positron plasma near the neutron star. Inside an outflow channel, the generated plasma flows away from the pulsar magnetosphere. A part of the plasma electrons returns and, being accelerated towards the star, regenerate the plasma by their curvature radiation. It is shown that plasma production near the star causes an appearance of positron and electron equatorial belts. The plasma concentration and the flux of the returning electrons are estimated. The portion of the energy entering into the pulsar magnetosphere and its dependence on pulsar parameters are estimated. 相似文献
2.
Satoshi Hinata 《Astrophysics and Space Science》1977,51(2):303-318
The possibility of radio emission is considered within a model which produces the beam-plasma system near the pulsar. A longitudinal instability develops near the light cylinder for a particular choice of parameters adopted in the paper. The excited wave strongly oscillates the beam particles perpendicular to its average velocity on one hand, and forms bunches of them on the other hand. Consequently, coherent radiation is expected. The frequency of the emission falls within the radio band, but the intensity turns out to be too low to explain observations. An appreciable enhancement of the beam number density over the Goldreich-Julian value (n
bB/2ec) is needed if the mechanism discussed in the present paper is responsible for the pulsar radio emission. 相似文献
3.
It is shown that knowing the energy flux density of the radio emission, the rate of increase in the period, and the distance
of a pulsar enables one to calculate all the rest of its most important characteristics (the solid angle of the radio emission
beam, the radio luminosity, the solid angle of the beam of γ rays, the energy flux density of the g-ray emission, and the
magnetic moment, moment of inertia, and mass of the neutron star). Equations from which these pulsar characteristics can be
calculated are given at the end of the paper. The results of calculations for a number of pulsars are given in Tables 2 and
3 as an illustration.
Translated from Astrofizika, Vol. 43, No. 2, pp. 277-291, April–June, 2000. 相似文献
4.
G. S. Sahakian 《Astrophysics》2000,43(1):111-126
The theory of pulsar radio emission has been developed in a series of our papers since 1992. It was shown that pulsar radio
emission is produced in the lower part of a channel of open magnetic field lines, in a region with a height h ≈ 1.1-107 μ
30
1/3
/P4/21 cm above a magnetic cap of the neutron star (P is the pulsar’s period and μ is the star’s magnetic moment). Here, owing to
vigorously occurring processes (the production of photons of curvature radiation and their annihilation into e+e- pairs), two ultrarelativistic particle fluxes are formed: an electron flux moving upward and a positron flux falling onto
the star’s magnetic cap. These main fluxes are accompanied by narrow strips of positron and electron fluxes of relatively
low energy, the curvature emission from which is a strong coherent radio source. The present paper is a review of earlier
papers, and important additions and refinements are also made. Equations are offered for the radio luminosity of a pulsar,
the solid angle of the radio beam, and the magnetic moment and moment of inertia of the pulsar’s neutron star.
Translated from Astrofizika, Vol. 43, No. 1, pp. 147-169, January–March, 2000. 相似文献
5.
The effect of a neutron-proton vortex system on the rotation dynamics of neutron stars is examined. The dynamics of the motion of a two component superfluid system in the core of a neutron star yields an equation for the evolution of the pulsar's rotation period. The spin down of the star owing to energy release at the core boundary, which is associated with a contraction of the length of the neutron vortex as it moves radially and magnetic energy of the vortical cluster is released, is taken into account. Evolutionary curves are constructed for pulsars with different magnetic fields and stellar radii. For certain values of the coefficient of friction between the superfluid and normal components in the core of the neutron star, at the end of its evolution a radio pulsar may become an anomalous x-ray pulsar or a source of soft gamma radiation with a period on the order of 10 seconds. 相似文献
6.
V. V. Zheleznyakov 《Astrophysics and Space Science》1971,13(1):87-99
A model of pulsars is discussed in which formation of a polar diagram of the radiation is influenced by the motion of the source around a neutron star with a velocity close to that of light. For a power-law frequency-spectrum of the radiation and isotropy of the diagram in a system of coordinates rotating with the source, the width of the observed pulse is shown to be independent of frequency.The proposed explanation of the second period characteristics of type CP 1919 pulsars is based on the effect of relativistic motion of the radiation source. The positions are established (relative to the axis of rotation of the star) of the local sources of radiation in the optical and in the radio ranges for the pulsar NP 0532. It is shown how the polarization characteristics of the optical radiation of this pulsar may be connected with the effects of relativistic orbiting of the source of radiation about the star. 相似文献
7.
A. A. Stepanian 《Astrophysics and Space Science》1982,84(2):347-361
According to the proposed model of the Cyg X-3, it should be recognized as a binary system consisting of a pulsar and an usual star. The plasma with the frozen-in field flows out from the star. The electromagnetic continuous spectrum in the range from radio to gamma radiation owes its origin to the interaction of electrons accelerated by a pulsar with the magnetic field of the stream. The influence of the inverse Compton effect on the spectral distribution of radiation has been considered by the numerical calculations of a system of kinetic equations. The calculations show remarkable agreement with the measurements, if the particle energy spectrum is expressed as dN/dE=AE
–2.2. The lower limit of the accelerated particle energy equals approximately 10–2 erg.The situation of the peak of gamma-quantum radiation of very high energy in respect to the minimum in the X-ray radiation can be explained in terms of the suggested model. 相似文献
8.
PSR B1259-63 is the only known binary system with a radio pulsar from which the non-pulsed radio and X-ray emission was detected.
The companion star in this system is a Be star SS 2883. A rapidly rotating radio pulsar is expected to produce a wind of relativistic
particles. Be stars are known to produce highly asymmetric mass loss. Due to the interaction of the pulsar wind and the Be
star wind the system of two shocks between the pulsar and the Be star forms. In this paper we show that the observed non-pulsed
radio emission from the system is a result of the synchrotron emission of the relativistic particles in the outflow beyond
the shock wave and that the non-pulsed X-ray emission is due to the inverse Compton scattering of the Be star photons on this
particles.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
We consider a system consisting of a neutron star surrounded by a disc of dense degenerate matter, and study the sequence of events following the impact of comets on to the disc. The direct signature of the impact event is a short burst of high-energy radiation (X-rays to UV, depending on the impact location) emitted from the bubble of hot gas created at the impact site. We assume that the bubble is confined by the magnetic field of the central neutron star. Part of the bubble matter may be channelled along magnetic field lines and rain down on the polar caps. The surface density at the neutron star surface may be sufficient to initiate a runaway thermonuclear reaction. These X-rays or the direct effect of the transferred plasma crossing charge-depleted regions in the outer magnetosphere may re-ignite an otherwise dead pulsar. 相似文献
10.
We present a numerical model of the action of a pulsar on its associated supernova remnant. The expansion of the blast wave
in the progenitor star has first been considered until radiation pressure within the ejected material becomes negligible due
to expansion. By assuming that expansion is ballistic and that the ejecta is opaque to the pulsar 's magnetodipole radiation,
the model produces a radiation-filled cavity which grows around the pulsar and contributes to power the dynamics of the forming
supernova remnant. The interface between the cavity and the ejecta has been modelled as a thin shell which, depending on the
initial spin frequency of the pulsar, can sweep through the ejecta and reach the blast wave. Results for the evolution of
the shell indicate that it may strike the front most part of the shocked gas some 60 years after the explosion. Such pulsar-supernova
remnant interactions are proposed to form the base of a new subclassification of pulsar-filled supernova remnants.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
The synchrotron mechanism of radiation from the Crab pulsar has been investigated on the assumption that the mechanism acts in a source moving with relativistic velocity round a neutron star. A detailed matching has been made of the theoretical spectra of synchrotron radiation from relativistic electrons with the results of measurements of the radiation flux from the Crab pulsar in the infrared, optical and X-ray ranges. The parameters of the radiating region (intensity of the magnetic field, source dimensions, density and lifetime of radiating electrons) have been found. They are expressed through the ratio of the energy density of the magnetic field in the source to that of radiating electrons. The level of Compton-radiation in this region is estimated. Possible values of at which the level will correspond to the available results of measurements of the-radiation flux from the Crab pulsar are given. An estimate is presented for the surface magnetic field of the neutron star which does not contradict those obtained from considerations of the magnetic flux conservation when compressing the object up to the neutron star dimensions. 相似文献
12.
《New Astronomy》2013
We investigate the effect of mass on the radiation of a relativistically rotating neutron star. The method of Haxton and Ruffini is used to find the radiation flux from a relativistically rotating neutron star. By extending the idea of a point charge orbiting a black hole, a pulsar is modeled by simulating a relativistically rotating magnetic dipole embedded within a neutron star. The resulting equations retain the mass of the neutron star, thereby introducing effects of general relativity on the radiation from the dipole. We present exact solutions to the modeling equation as well as plots of energy spectra at different rotational velocities and inclination angles. We also present plots of total energy versus mass and two tables containing a comparison of energy ratios. These demonstrate that, for realistic neutron star masses, the high speed enhancement of the radiation is always more than compensated by the frame dragging effect, leading to a net reduction of radiation from the star. It is found that the inclusion of mass not only reduced the special relativistic enhancement, but negates it entirely as the mass of the neutron star approaches the mass limit. 相似文献
13.
The aim of this article is to draw attention to the importance of the electric current loss in the energy output of radio
pulsars. We remind that even the losses attributed to the magneto-dipole radiation of a pulsar in vacuum can be written as
a result of an Ampere force action of the electric currents flowing over the neutron star surface (see the books of Michel
(Theory of Neutron Star Magnetosphere. University of Chicago Press (1991)) and of Beskin, Gurevich and Istomin (Physics of the Pulsar Magnetosphere. Cambridge Univ. Press (1993)). It is this force that is responsible for the transfer of angular momentum of a neutron star
to an outgoing magneto-dipole wave. If a pulsar is surrounded by plasma, and there is no longitudinal current in its magnetosphere,
there is no energy loss. It is the longitudinal current closing within the pulsar polar cap that exerts the retardation torque
acting on the neutron star. This torque can be determined if the structure of longitudinal current is known. Here we remind
of the solution by Beskin, Gurevich and Istomin (ed. cit.) and discuss the validity of such an assumption. The behavior of
the recently observed “part-time job” pulsar B1931+24 can be naturally explained within the model of current loss while the
magneto-dipole model faces difficulties.
This work was partially supported by the Russian Foundation for Basic Research (Grant no. 05-02-17700) and Dynasty fund. Elena
Nokhrina thanks the Conference Organizing Committee for the PPARC/Padova University Grant, and the RFFR for the travel grant
(no. 06-02-26645). 相似文献
14.
We present a calculation of a three-dimensional pulsar magnetosphere model to explain high-energy emission from the Geminga pulsar with a thick outer gap. High-energy γ -rays are produced by primary accelerated particles with a power-law energy distribution through curvature radiation inside the outer gap. We also calculate the emission pattern, pulse profile and phase-resolved spectra of high-energy γ -rays of the Geminga pulsar, and find that its pulse profile is consistent with the observed one if the magnetic inclination and viewing angle are ∼50° and ∼86° respectively. We describe the relative phases among soft (thermal) X-rays, hard (non-thermal) X-rays, and γ -rays. Our results indicate that X-ray and γ -ray emission from the Geminga pulsar may be explained by the single thick outer gap model. Finally, we discuss the implications of the radio and optical emission of the Geminga pulsar. 相似文献
15.
We find that in general relativity slow down of the pulsar rotation due to the magnetodipolar radiation is more faster for
the strange star with comparison to that for the ordinary neutron star of the same mass. Comparison with astrophysical observations
on pulsars spindown data may provide an evidence for the strange star existence and, thus, serve as a test for distinguishing
it from the neutron star. 相似文献
16.
I. F. Mirabel 《Astrophysics and Space Science》2007,309(1-4):267-270
Recent observations have shown that some compact stellar binaries radiate the highest energy light in the universe. The challenge
has been to determine the nature of the compact object and whether the very high energy gamma-rays are ultimately powered
by pulsar winds or relativistic jets. Multiwavelength observations have shown that one of the three gamma-ray binaries known
so far, PSR B1259−63, is a neutron star binary and that the very energetic gamma-rays from this source and from another gamma-ray
binary, LS I +61 303, may be produced by the interaction of pulsar winds with the wind from the companion star. At this time
it is an open question whether the third gamma-ray binary, LS 5039, is also powered by a pulsar wind or a microquasar jet,
where relativistic particles in collimated jets would boost the energy of the wind from the stellar companion to TeV energies.
I.F. Mirabel is on leave from CEA, France. 相似文献
17.
K. H. Tsui 《Solar physics》1996,168(1):171-182
The generation of bright solar radio spikes by the beam-driven cyclotron resonance maser mechanism (the resonant interaction of an electron beam with a circularly polarized wave in a background plasma under the action of a guide magnetic field) is studied. Nonlinear effects such as radiation damping and gyrophase bunching on electron energy and momentum are responsible for the enhanced direct energy conversion between the beam and the coherent wave. Factors such as beam energy spread and pitch angle distribution are analyzed. The intense maser radiation is carried at the source by the circularly polarized wave propagating along the magnetic field. Due to the magnetic field curvature, the outgoing maser radiation converts into extraordinary and ordinary modes. The extraordinary mode suffers from plasma absorption at the second harmonic layer, whereas the ordinary mode is likely to get through. 相似文献
18.
Xiaohu Yang H. J. Mo Frank C. van den Bosch Simone M. Weinmann Cheng Li Y. P. Jing 《Monthly notices of the Royal Astronomical Society》2005,362(2):711-726
Some massive binaries should contain energetic pulsars which inject relativistic leptons from their inner magnetospheres and/or pulsar wind regions. If the binary system is compact enough, then these leptons can initiate inverse Compton (IC) e± pair cascades in the anisotropic radiation field of a massive star. γ-rays can be produced in the IC cascade during its development in a pulsar wind region and above a shock in a massive star wind region where the propagation of leptons is determined by the structure of a magnetic field around the massive star. For a binary system with specific parameters, we calculate phase-dependent spectra and fluxes of γ-rays escaping as a function of the inclination angle of the system and for different assumptions on injection conditions of the primary leptons (their initial spectra and location of the shock inside the binary). We conclude that the features of γ-ray emission from such massive binaries containing energetic pulsars should allow us to obtain important information on the acceleration of particles by the pulsars, and on interactions of a compact object with the massive star wind. Predicted γ-ray light curves and spectra in the GeV and TeV energy ranges from such binary systems within our Galaxy and Magellanic Clouds should be observed by future AGILE and GLAST satellites and low-threshold Cherenkov telescopes, such as MAGIC, HESS, VERITAS or CANGAROO III. 相似文献
19.
A. S. Zentsova 《Astrophysics and Space Science》1983,95(2):459-462
A hypothesis is being put forward that the formation of jets in the nuclei of radio galaxies is due to a high-speed energy excretion (explosion) in the accretion disk around a massive black hole. The explosion can be induced, for example, by a fall of the star into the black hole. For the accretion disk featuring an exponential high-density distribution, an asymmetrical explosion can be obtained: the shock front moves in the direction of decreasing the density accelerately and achieves the relativistic velocity swiftly, carrying away the most fraction of the explosion energy. Radio emission of the jet involves synchrotron radiation of relativistic electrons which are accelerated by such shock wave in the magnetic field driven up by the shock front. 相似文献
20.
In this work a new family of relativistic models of electrically charged compact star has been obtained by solving Einstein–Maxwell field equations with preferred form of one of the metric potentials and a suitable form of electric charge distribution function. The resulting equation of state (EOS) has been calculated. The relativistic stellar structure for matter distribution obtained in this work may reasonably models an electrically charged compact star whose energy density associated with the electric fields is on the same order of magnitude as the energy density of fluid matter itself (e.g. electrically charged bare strange stars). Based on the analytic model developed in the present work, the values of the relevant physical quantities have been calculated by assuming the estimated masses and radii of some well known strange star candidates like X-ray pulsar Her X-1, millisecond X-ray pulsar SAX J 1808.4-3658, and 4U 1820-30. 相似文献