Second‐Harmonic Plasma Radiation of Magnetically Trapped Electrons in Stellar Coronae

Stepanov, A. V.; Kliem, B.; Krüger, A.; Hildebrandt, J.; Garaimov, V. I.

doi:10.1086/307835

Cited by 43 publications

(16 citation statements)

References 49 publications

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“…The latter scenario may arise either from Coulomb collisions if in the lower parts of the loop there is higher plasma density or from an enhanced level of turbulence there. Stepanov et al (2007) have argued that strong scattering of electrons by whistlers can account for the observed evolution of fast collimated ejections of nonthermal electrons reported by Yokoyama et al (2002).…”

Section: Anisotropies and The Effect Of The Ambient Mediummentioning

confidence: 95%

“…A popular idea is that they represent a signature of highly fragmented energy release in flares . Theoretical models that propose that the spikes come from sources located in the acceleration site of the flare have been developed (e.g., Kuijpers, van der Post, and Slottje, 1981;Tajima et al, 1990;Stepanov et al, 1999). More recently, Bárta and Karlický ( , 2005 have developed a model (see also Section 5.2) in which decimeter spikes can be generated in the turbulent plasma of reconnection outflows.…”

Section: Narrowband Spikesmentioning

confidence: 99%

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Radio Emission of Flares and Coronal Mass Ejections

et al. 2008

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We review recent progress on our understanding of radio emission from solar flares and coronal mass ejections (CMEs) with emphasis on those aspects of the subject that help us address questions about energy release and its properties, the configuration of flare -CME source regions, coronal shocks, particle acceleration and transport, and the origin of solar energetic particle (SEP) events. Radio emission from electron beams can provide information about the electron acceleration process, the location of injection of electrons in the corona, and the properties of the ambient coronal structures. Mildly relativistic electrons gyrating in the magnetic fields of flaring loops produce radio emission via the gyrosynchrotron mechanism, which provides constraints on the magnetic field and the properties of energetic electrons. CME detection at radio wavelengths tracks the eruption from its early phase and reveals the participation of a multitude of loops of widely differing scale. Both flares and CMEs can ignite shock waves and radio observations offer the most robust tool to study them. The incorporation of radio data into the study of SEP events reveals that a clear-cut distinction between flare-related and CME-related SEP events is difficult to establish.

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Section: Anisotropies and The Effect Of The Ambient Mediummentioning

confidence: 95%

Section: Narrowband Spikesmentioning

confidence: 99%

Radio Emission of Flares and Coronal Mass Ejections

et al. 2008

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“…This upper limit has also been estimated theoretically (Mel'Nik 1994). For plasma emission, T B is expected to be less than 10 16 K (Stepanov et al 1999(Stepanov et al , 2001. However, for a certain type of plasma emission from double layers, T B could reach 10 25 K (Kuijpers 1989).…”

Section: Distance To the Gcrt And Its Classificationmentioning

confidence: 99%

Circularly Polarized Emission From the Transient Bursting Radio Source GCRT J1745 – 3009

Roy

Hyman

Pal

et al. 2010

ApJ

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We report detection of strong circularly polarized emission from the transient bursting source GCRT J1745-3009 based on new analysis of 325 MHz GMRT observations conducted on 28 September 2003. We place 8 R ⊙ as the upper limit on the size of the emission region. The implied high brightness temperature required for an object beyond 1 pc and the high fraction of circular polarization firmly establish the emission as coherent. Electron cyclotron or plasma emission from a highly subsolar magnetically dominated dwarf located ≤4 kpc away could have given rise to the GCRT radio emission.

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“…They have been studied in many papers (Slottje 1981;Karlický 1984;Fu et al 1985;Stähli & Magun 1986;Güdel 1990;Krucker & Benz 1994;Aschwanden et al 1998) and two classes of models have been suggested: a) based on the plasma emission mechanism (Kuijpers et al 1981;Tajima et al 1990;Wentzel 1991;Stepanov et al 1999), and b) based on the electroncyclotron maser mechanism (Wu & Lee 1979;Holman et al 1980;Melrose & Dulk 1982;Vlahos & Sharma 1984;Winglee et al 1988;Aschwanden 1990;Fleishman & Yastrebov 1994;Willes & Robinson 1996;Fleishman & Melnikov 1998). The statistical methods (Schwarz et al 1993) applied to spike events show that the spectral structure of spikes is not stochastic and that neighboring spikes are correlated.…”

Section: Introductionmentioning

confidence: 99%

Turbulent plasma model of the narrowband dm-spikes

Bárta

Karlický

2001

A&A

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Abstract. Starting from radio spectrum features of the narrowband dm-spikes, it is suggested that they are generated at positions in the solar flare atmosphere where the upper hybrid frequency is equal to the low harmonics of the electron cyclotron frequency. It is assumed that a radio source plasma is in a turbulent state. The upper hybrid waves are generated by an anisotropic electron beam which propagates along magnetic loop lines. Collisional damping and turbulent changes of plasma parameters in the radio source cause strong intensity-frequency variations of the upper hybrid waves. These waves are then transformed into observed narrowband dm-spikes. Using this model, the artificial radio spectra are computed. It is shown that a chain of narrowband spikes is generated at a one cyclotron harmonic, in one turbulent magnetic flux tube. On the other hand, a cloud of spikes (or their harmonic clouds) results from a superposition of many chains of spikes generated in many turbulent magnetic flux tubes (in several cyclotron harmonics). Finally, further features of the narrowband dm-spikes are discussed in the framework of the proposed model.

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Second‐Harmonic Plasma Radiation of Magnetically Trapped Electrons in Stellar Coronae

Cited by 43 publications

References 49 publications

Radio Emission of Flares and Coronal Mass Ejections

Radio Emission of Flares and Coronal Mass Ejections

Circularly Polarized Emission From the Transient Bursting Radio Source GCRT J1745 – 3009

Turbulent plasma model of the narrowband dm-spikes

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