Theory of solar bursts

Takakura, T.

doi:10.1007/bf00151359

Cited by 94 publications

(30 citation statements)

References 66 publications

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“…It also appears very likely that non-thermal electrons in this energy range are degraded mostly by collisions with ambient plasma particles (e.g. Takakura, 1969;Holt and Ramaty, 1969). However, it is not yet clear whether this degradation occurs in a characteristic time which is short or long compared to the decay time of the burst.…”

Section: Introductionmentioning

confidence: 98%

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The decay characteristics of models of solar hard X-ray bursts

Brown

1972

Sol Phys

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Abstraet. Models of solar hard X-ray bursts are considered in which non-thermal electrons are impulsively injected into a coronal magnetic trap. Recognising that the ends of the trap are likely to be rooted in the photosphere and that the density of the ambient atmosphere may thus be highly non-uniform along the field lines, it is shown that the X-ray spectra will initially soften with time, due to collisions, when this non-uniformity is strong enough. This removes a well-known discrepancy in models with uniform density.It is shown also that non-uniformity steepens the electron spectrum required to produce a given observed X-ray spectrum. In consequence the total non-thermal electron energy involved in a given burst is greater than that previously inferred from impulsive injection models.

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Section: Introductionmentioning

confidence: 98%

“…Peterson and Winckler, 1959;Takakura and Kai, 1966;Korchak, 1967). It also appears very likely that non-thermal electrons in this energy range are degraded mostly by collisions with ambient plasma particles (e.g.…”

Section: Introductionmentioning

confidence: 99%

The decay characteristics of models of solar hard X-ray bursts

Brown

1972

Sol Phys

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“…It is the basis of the radiation processes by electrons in a magnetic field or an intense circular polarized light field, which are known as cyclotron/synchrotron radiation or Thomson/Compton scattering. Because they play important roles in astrophysics, plasma physics and accelerator physics, the radiation from an electron in circular/spiral motion has been addressed in many textbooks 14,15 and literature 16,17 . However, surprisingly, no study has discussed its phase structure or angular momentum for more than one hundred years.…”

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confidence: 99%

Angular Momentum of Twisted Radiation from an Electron in Spiral Motion

et al. 2017

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We theoretically demonstrate for the first time that a single free electron in circular/spiral motion emits twisted photons carrying well defined orbital angular momentum along the axis of the electron circulation, in adding to spin angular momentum. We show that, when the electron velocity is relativistic, the radiation field contains harmonic components and the photons of l-th harmonic carry  l total angular momentum for each. This work indicates that twisted photons are naturally emitted by free electrons and more ubiquitous in laboratories and in nature than ever been thought.

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“…However, the ultra-relativistic approach was not enough to explain the solar case, in contrast to the cases of the majority of the cosmic objects (Ginzburg 1964). An extensive review of this topic was presented by Takakura (1967). The gyrosynchrotron radiation is produced by mildly relativistic electrons moving in a magnetic field, and the microwave emission from solar flares is typically generated by non-thermal electron distributions, commonly described as a power law distribution.…”

Section: Introductionmentioning

confidence: 99%

Solar bursts gyrosynchrotron emission from three-dimensional sources

Simões

Costa

2006

A&A

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Aims. In this study we have analyzed the spectral and spatial characteristics of gyrosynchrotron emission and the polarization of solar bursts in a highly inhomogeneous medium. Our main goal was to investigate the effects of the geometry of the source on the resulting spectrum. Methods. The SOHO/EIT and TRACE high resolution images revealed structured magnetic configurations in detail over solar active regions. In our method, we represent the magnetic field geometry by three-dimensional structures obtained from magnetic field extrapolation, tomography, or any geometry that resembles the observed structures. The gyrosynchrotron radiation was numerically calculated through a modified version of Ramaty's code. Results. We calculated the radiation produced by non-thermal electron distributions in this complex environment and solved the radiative transfer equation. The results, presented in brightness distribution maps, polarization maps, and spectra, are discussed. Our numerical results agree with statistical analyses of observed spectra present in the literature. We note a spectral broadening due to the spatial and intensity inhomogeneity of the magnetic field and no center-to-limb variations, which cannot be explained by homogeneous source models. The computed maps revealed a non uniform brightness distribution, with small-scale structures, and different spatial characteristics in each frequency. Also, we found different spectral characteristics at different regions of the emitting source. Polarization maps reveal its high dependence on geometry and on the position of the source on the solar disk.

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Theory of solar bursts

Abstract: 01 = (0,,(1 (1 come cos0) -* , (2.4)where (0n=27rfi~=eH/moc, which is angular gyro-frequency. The first bracket of

Cited by 94 publications

References 66 publications

The decay characteristics of models of solar hard X-ray bursts

The decay characteristics of models of solar hard X-ray bursts

Angular Momentum of Twisted Radiation from an Electron in Spiral Motion

Solar bursts gyrosynchrotron emission from three-dimensional sources

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