2002 August 24 Limb Flare Loop: Dynamics of Microwave Brightness Distribution

Reznikova, Veronika; Melnikov, V. F.; Shibasaki, Κ.; Gorbikov, S. P.; Pyatakov, Nikolai P.; Myagkova, I. N.; Ji, H.

doi:10.1088/0004-637x/697/1/735

Cited by 63 publications

(37 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We suggest that this spatial QPP distribution is not the pulsation mode property, but is connected with the properties of the acceleration and transport of energetic electrons. It was found from the model simulations (Melnikov et al 2002;Gorbikov & Melnikov 2007;Reznikova et al 2009) that the absence of the emission peaks in the LT can be a natural consequence of anisotropic injection of accelerated electrons near to the loop apex predominantly along magnetic field lines. In this case the injected electrons pass quickly though the upper part of the loop with almost zero pitch-angle and, therefore, effectiveness of their gyrosynchrotron emission there is very low.…”

Section: Spatial Distribution Of Qpp and Modulation Depthmentioning

confidence: 99%

Flare quasi-periodic pulsations with growing periodicity

Reznikova

Shibasaki

2010

A&A

Self Cite

View full text Add to dashboard Cite

We conducted a wavelet analysis of the flare intensity variations for the long duration flare on 2005 August 22 observed with the Nobeyama Radioheliograph at frequencies 17 and 34 GHz and with the Ramaty High Energy Solar Spectroscopic Imager at 25-50 keV. We found that the signals contain a well-pronounced periodicity in which the oscillation period grows from 2.5 to 5 min. An analysis of the loop length and plasma temperature evolution during the flare allowed us to interpret the quasi-periodic pulsations in terms of the second standing harmonics of the slow magnetoacoustic mode. This mode can be generated by the initial impulsive energy release and work as a trigger for the repeated energy releases.

show abstract

Section: Spatial Distribution Of Qpp and Modulation Depthmentioning

confidence: 99%

Flare quasi-periodic pulsations with growing periodicity

Reznikova

Shibasaki

2010

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…By far the favorite loop event for radio studies during the RHESSI period is SOL2002-08-24T01:12 (X3.1) on the west limb (Karlický 2004;Li & Gan 2005;Melnikov 2006;Tzatzakis et al 2008;Romano et al 2009;Reznikova et al 2009;, which also produced a fast (1900 km s −1 ) CME and an energetic particle event at the Earth. Figure 5.1 shows images in HXRs, microwaves and the EUV 195Å band (Fe XII and Fe XXIV) during the early part of the impulsive phase, for which RHESSI data are available.…”

Section: "Loop" Flaresmentioning

confidence: 99%

The Relationship Between Solar Radio and Hard X-ray Emission

White¹,

Benz²,

Christe³

et al. 2011

High-Energy Aspects of Solar Flares

View full text Add to dashboard Cite

This review discusses the complementary relationship between radio and hard X-ray observations of the Sun using primarily results from the era of the Reuven Ramaty High Energy Solar Spectroscopic Imager satellite. A primary focus of joint radio and hard X-ray studies of solar flares uses observations of nonthermal gyrosynchrotron emission at radio wavelengths and bremsstrahlung hard X-rays to study the properties of electrons accelerated in the main flare site, since it is well established that these two emissions show very similar temporal behavior. A quantitative prescription is given for comparing the electron energy distributions derived separately from the two wavelength ranges: this is an important application with the potential for measuring the magnetic field strength in the flaring region, and reveals significant differences between the electrons in different energy ranges. Examples of the use of simultaneous data from the two wavelength ranges to derive physical conditions are then discussed, including the case of microflares, and the comparison of images at radio and hard X-ray wavelengths is presented. There have been puzzling results obtained from observations of solar flares at millimeter and submillimeter wavelengths, and the comparison of these results with corresponding hard X-ray data is presented. Finally, the review discusses the association of hard X-ray releases with radio emission at decimeter and meter wavelengths, which is dominated by plasma emission (at lower frequencies) and electron cyclotron maser emission (at higher frequencies), both coherent emission mechanisms that require small numbers of energetic electrons. These comparisons show broad general associations but detailed correspondence remains more elusive.

show abstract

“…Therefore HXR and microwave flare observations, particularly during the initial impulsive phase, offer valuable clues about the physics of the particle-acceleration process (e.g., Holman et al 2011). Decades of study have established that these emissions often are highly variable in time (e.g., Parks & Winckler 1969;Chiu 1970;Kane et al 1983;Kiplinger et al 1983Kiplinger et al , 1984Machado et al 1993;Aschwanden et al 1995) and originate at both the tops and footpoints of coronal loops (Marsh & Hurford 1980;Hoyng et al 1981;Masuda et al 1994;Reznikova et al 2009;Caspi & Lin 2010;Ishikawa et al 2011). More recently, a second coronal source has been discovered above the loop-top coronal source Sui et al 2004;Pick et al 2005;Liu et al 2008Liu et al , 2013Su et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Magnetic-Island Contraction and Particle Acceleration in Simulated Eruptive Solar Flares

Guidoni

DeVore

Karpen

et al. 2016

ApJ

View full text Add to dashboard Cite

The mechanism that accelerates particles to the energies required to produce the observed high-energy impulsive emission in solar flares is not well understood. Drake et al. proposed a mechanism for accelerating electrons in contracting magnetic islands formed by kinetic reconnection in multi-layered current sheets (CSs). We apply these ideas to sunward-moving flux ropes (2.5D magnetic islands) formed during fast reconnection in a simulated eruptive flare. A simple analytic model is used to calculate the energy gain of particles orbiting the field lines of the contracting magnetic islands in our ultrahigh-resolution 2.5D numerical simulation. We find that the estimated energy gains in a single island range up to a factor of five. This is higher than that found by Drake et al. for islands in the terrestrial magnetosphere and at the heliopause, due to strong plasma compression that occurs at the flare CS. In order to increase their energy by two orders of magnitude and plausibly account for the observed high-energy flare emission, the electrons must visit multiple contracting islands. This mechanism should produce sporadic emission because island formation is intermittent. Moreover, a large number of particles could be accelerated in each magnetohydrodynamic-scale island, which may explain the inferred rates of energetic-electron production in flares. We conclude that island contraction in the flare CS is a promising candidate for electron acceleration in solar eruptions.

show abstract

2002 August 24 Limb Flare Loop: Dynamics of Microwave Brightness Distribution

Cited by 63 publications

References 30 publications

Flare quasi-periodic pulsations with growing periodicity

Flare quasi-periodic pulsations with growing periodicity

The Relationship Between Solar Radio and Hard X-ray Emission

Magnetic-Island Contraction and Particle Acceleration in Simulated Eruptive Solar Flares

Contact Info

Product

Resources

About