Transition Radio Emission of Mildly Relativistic Particles

1994 ◽  
pp. 243-244
Author(s):  
G. D. Fleishman ◽  
K. Yu. Platonov
Keyword(s):  
Radio Emission ◽  
Relativistic Particles

scholarly journals Jupiter's Radiation Belts and Upper Atmosphere

1974 ◽  
Vol 65 ◽  
pp. 375-383
Author(s):  
Joseph J. Degioanni ◽  
John R. Dickel
Keyword(s):  
Radio Emission ◽  
Radiation Belts ◽  
Upper Atmosphere ◽  
Mixing Ratio ◽  
Frequency Range ◽  
Emission Data ◽  
High Energies ◽  
Isotropic Distribution ◽  
Relativistic Particles ◽  
Flat Distribution

Models of Jupiter's radiation belts have been constructed to determine the distribution of particles and their energies which will produce the observed decimetric radio emission. Data on the spectrum and the variation of emission with Jovian longitude have been used to show that the relativistic particles have a nearly isotropic distribution with high energies (of order 100 MeV) within 2 Jovian radii and a very flat distribution in the equatorial plane of low energy particles further out in the magnetosphere.Subtraction of the emission predicted by this model from the total radio emission shows that the thermal contribution in the frequency range between 3000 and 10000 MHz is somewhat less than had been previously expected. (The brightness temperature of the planetary disk is 180 K at 3000 MHz, for example.) This suggests that the ammonia mixing ratio in Jupiter's upper atmosphere may be as high as 0.002.

Supernova Remnants: A Generalized Theoretical Approach to the Radio Evolution

1979 ◽  
Vol 3 (5) ◽  
pp. 343-347 ◽  
Author(s):  
J. L. Caswell ◽  
I. Lerche
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Interstellar Medium ◽  
Theoretical Approach ◽  
Supernova Remnants ◽  
Theoretical Work ◽  
Relativistic Particles

Theoretical work on the radio emission from supernova remnants (SNRs) has not developed much since the pioneering work of Shklovsky (1960) and van der Laa (1962a, b). Despite agreement that the emission results from the synchrotron process, the origin of the relativistic particles and magnetic field is not clear. There are three reasonable alternatives: (i) particles and field originate within the ejected material (e.g. Shklovsky 1960);(ii) both field and particles originate in the compressed interstellar medium (e.g. van der Laan 1962a);(iii) the field is interstellar but the particles are from the ejecta (as outlined by van der Laan 1962b).

scholarly journals Models of particle acceleration in galaxy clusters by MHD turbulence

2009 ◽  
Vol 5 (H15) ◽  
pp. 466-467
Author(s):  
G. Brunetti
Keyword(s):  
Particle Acceleration ◽  
Radio Emission ◽  
Galaxy Clusters ◽  
Indirect Evidence ◽  
Mhd Turbulence ◽  
Radio Data ◽  
Central Cluster ◽  
Relativistic Particles

AbstractPresent radio data provide indirect evidence that diffuse radio emission in the central cluster regions may originate from turbulent-acceleration of relativistic particles. I was invited to discuss models of particle acceleration by MHD turbulence in clusters and in these pages I briefly touch the main points of my talk.

scholarly journals Radio Emission from Close Binary Systems and Novae

1977 ◽  
Vol 42 ◽  
pp. 279-291
Author(s):  
R.M. Hjellming
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Binary Systems ◽  
Close Binary ◽  
X Ray ◽  
Close Binary Systems ◽  
Nova Shells ◽  
The Subject ◽  
Continuum Radio ◽  
Relativistic Particles

This review of the radio emission properties of close binary systems and novae will be partly concerned with surveying the star systems that exhibit continuum radio emission, and partly concerned with discussing the implications of the observed radio emission. The phenomena we will encounter will range from purely thermal continuum radio emission for the case of ionized nova shells to strong, non-thermal continuum radio emission produced by relativistic particles in both ‘normal’ and X-ray emitting close binary systems. In keeping with the subject of this symposium, let me emphasize that all regions involving radio emission are from the portions of the stellar environment where Ne ≤ 1010cm-3, generally rather high in the stellar or systemic atmosphere; however, events more closely associated with the stars themselves are the root causes of the phenomena, supplying energy, mass, magnetic fields, and relativistic particles.

scholarly journals Applications of Ohm’s Law to the pulsar magnetosphere

2000 ◽  
Vol 177 ◽  
pp. 379-380
Author(s):  
Thomas Kunzl ◽  
Harald Lesch ◽  
Axel Jessner
Keyword(s):  
Neutron Star ◽  
Radio Emission ◽  
Field Emission ◽  
Emission Model ◽  
Pulsar Magnetosphere ◽  
Inner Magnetosphere ◽  
Typical Particle ◽  
Vacuum Fields ◽  
Star Surface ◽  
Relativistic Particles

AbstractWe show that in the inner magnetosphere of a pulsar mildly relativistic particles can flow out steadily under two assumptions: i) all vacuum fields are completely shielded by copious amounts of particles drawn out by thermal and field emission (which is likely as shown in Jessneret al, 1999) ii) particles emitted from the neutron star surface have weakly relativistic energies (βϒ≈ 1). The results are consistent with the typical particle energies predicted in the radio emission model by Kunzlet al., 1999.

scholarly journals Observational Constraints on the Structure of the Pulsar Magnetic Field

1992 ◽  
Vol 128 ◽  
pp. 1-6
Author(s):  
A. D. Kuz'min
Keyword(s):  
Radio Emission ◽  
Plasma Frequency ◽  
Hollow Cone ◽  
Pulsar Radio ◽  
Cone Model ◽  
Curvature Radiation ◽  
Adopted Model ◽  
Magnetic Poles ◽  
Relativistic Particles ◽  
Pulsar Radio Emission

The most widely adopted model of pulsar radio emission is the hollow cone model, which fits much of the experimental data. The pulsar radio emission in this model is curvature radiation of relativistic particles flowing from the magnetic poles of the neutron star along a cone of open magnetic lines. The curvature radiation is amplified at the plasma frequency, therefore different radio frequencies f originate at different radii r of the emitting regions.

scholarly journals Hubble Space Telescope Observations of Synchrotron Jets

1994 ◽  
Vol 142 ◽  
pp. 909-916
Author(s):  
W. B. Sparks ◽  
J. A. Biretta ◽  
F. Macchetto
Keyword(s):  
Radio Emission ◽  
Hubble Space Telescope ◽  
Detailed Comparison ◽  
Synchrotron Emission ◽  
Space Telescope ◽  
X Ray ◽  
Radio Lobe ◽  
First Time ◽  
Relativistic Particles ◽  
Single Power

AbstractThe Hubble Space Telescope for the first time enables optical and UV images of jets to be obtained with spatial resolution comparable to radio interferometric techniques. Because synchrotron emission at these wavelengths is a diagnostic of particles several orders of magnitude higher in energy and correspondingly shorter in lifetime than those probed by radio, the sites of particle acceleration may be more readily identified in the optical and UV. Short-lifetime optical synchrotron emission in the SE inner radio lobe of M87 argues strongly for the presence of an invisible counterjet. A detailed comparison of HST and VLA images of the M87 jet shows there are very strong similarities in overall morphology, but that there are also significant differences. The optical and UV radiation is more localized within the knots than the radio emission and appears more confined toward the jet center. These differences may arise from localized shocks, sited at the optical knots with diffusion of relativistic particles away from those knots, or else they may be due to nonuniform magnetic fields and distributed acceleration processes. The UV fluxes of the knots are consistent with a single power law from optical to X-ray. Optical jets in other radio galaxies show diverse properties—the jet of PKS 0521–36 is smoothly resolved by HST while that of 3C 66B shows previously unsuspected filmentary structure. Likewise, the jet of 3C 273 shows newly observed optical filaments and an intensity distribution quite unlike that of the radio emission. Like M87, the optical jet of 3C 273 is narrower than the radio jet. The serendipitous discovery of a new optical synchrotron jet in 3C 264 suggests that optical jets may be relatively common.Subject heading: galaxies: jets

scholarly journals Plasma Instabilities: Sources for Coherent Radio Emission

1996 ◽  
Vol 160 ◽  
pp. 147-154 ◽  
Author(s):  
Estelle Asseo
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Plasma Emission ◽  
Pulsar Radio ◽  
Degree Of Coherence ◽  
Plasma Effects ◽  
Coherent Emission ◽  
Collective Plasma ◽  
Relativistic Particles ◽  
Pulsar Radio Emission

AbstractThe mechanism for the generation of pulsar radio emission has not yet been identified. Several coherent emission processes, linked to the motion of relativistic particles in the extremely strong pulsar magnetic field, have been proposed as possible candidates. Essential improvements, based on fundamental concepts of plasma physics, prove that collective plasma effects can provide the necessary degree of coherence. Progress in the 1990s, which is reported here, relates to curvature maser emission processes and relativistic plasma emission mechanisms.

scholarly journals Periodic Radio Emission from the Helium Rich Stars HD 37017 and σ Ori E

1993 ◽  
Vol 138 ◽  
pp. 541-546
Author(s):  
Francesco Leone ◽  
Grazia Umana
Keyword(s):  
Radio Emission ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Gyrosynchrotron Emission ◽  
Equatorial Belt ◽  
Field Lines ◽  
Chemically Peculiar Stars ◽  
Magnetic Poles ◽  
First Time ◽  
Relativistic Particles

AbstractDrake et al. (1987) detected, for the first time, radio emission from magnetic Chemically Peculiar stars. They suggested that radio emission is consistent with gyrosynchrotron emission from continuously injected, mildly, relativistic particles trapped in a magnetic equatorial belt.Leone (1991) showed that it is possible considering that the radio emission comes from magnetic poles and is due to the electron component of the wind flowing along the open field lines. As a consequence Leone (1991) put forward the hypothesis that such emission could be periodically variable.In order to verify the surmise of a periodic radio emission, the magnetic Chemically Peculiar stars HD 37017 and σ Ori E have been monitored with the VLA at 6 cm.By combining our data with those obtained by Drake et al. (1987) and Philips & Lestrade (1988), we show that the radio emission from HD 37017 and σ Ori E varies with the rotational period.

scholarly journals Radio Emission from SN 1987A

1996 ◽  
Vol 145 ◽  
pp. 309-315 ◽  
Author(s):  
L. Staveley-Smith ◽  
R. N. Manchester ◽  
A. K. Tzioumis ◽  
J. E. Reynolds ◽  
D. S. Briggs
Keyword(s):  
Radio Emission ◽  
Radio Observations ◽  
Density Profiles ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Supernova 1987A ◽  
Radio Outburst ◽  
Post Shock ◽  
Two Phases ◽  
Relativistic Particles

We review the first six years of radio observations of Supernova 1987A. The evolution can be divided into two phases: the initial radio outburst which lasted a few weeks, and the period from mid-1990 to the present, during which the radio emission has steadily increased. Both phases can be explained by a small fraction (0.1-0.5%) of the post-shock thermal energy being converted to energy in relativistic particles and magnetic fields, which give rise to synchrotron radiation. The optical depths, densities and density profiles for the pre-shocked circumstellar material are somewhat different for the two phases, but consistent with models of the density structure of the material within the circumstellar ring. New high-resolution radio observations show that the SN shock front is already at about three-quarters of the radius of the circumstellar ring, and that there exists a bright equatorial component of emission aligned with this ring which is probably due to a polar density gradient in the ‘hourglass’ structure.

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