Cosmic Electrodynamics

Fleishman, G. D.; Топтыгин, И. Н.

doi:10.1007/978-1-4614-5782-4

Cited by 40 publications

(28 citation statements)

References 198 publications

(275 reference statements)

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“…Turbulence or plasma waves, for example, can be generated by the interaction of the high speed flows with the ambient corona. Upon cascading to smaller scales (comparable to the gyro-radii of background particles) at some distance from the reconnection site, turbulence can accelerate the particles and heat the plasma (Hamilton & Petrosian 1992;Miller et al 1996;Chandran 2003;Petrosian et al 2006;Jiang et al 2009;Fleishman & Toptygin 2013). Additional contribution to particle acceleration and/or heating can come from fast-mode shocks in the outflow regions (Forbes & Priest 1983;Tsuneta & Naito 1998;Guo & Giacalone 2012;Nishizuka & Shibata 2013), gas dynamic shocks within contracting flux tubes (Longcope et al 2009), and the first-order Fermi and betatron mechanisms within the collapsing traps formed by contracting loops (Somov & Kosugi 1997;Karlický & Kosugi 2004;Karlický 2006;Grady et al 2012).…”

Section: Proposed Physical Picturementioning

confidence: 99%

Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows

Liu

Chen

Petrosian

2013

ApJ

207

203

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Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional outflows in forms of plasmoid ejections and contracting cuspshaped loops originate between an erupting flux rope and underlying flare loops at speeds of typically 200-300 km s −1 up to 1050 km s −1 . These outflows are associated with spatially separated double coronal X-ray sources with centroid separation decreasing with energy. The highest temperature is located near the nonthermal X-ray loop-top source well below the original heights of contracting cusps near the inferred reconnection site. These observations suggest that the primary loci of particle acceleration and plasma heating are in the reconnection outflow regions, rather than the reconnection site itself. In addition, there is an initial ascent of the X-ray and EUV loop-top source prior to its recently recognized descent, which we ascribe to the interplay among multiple processes including the upward development of reconnection and the downward contractions of reconnected loops. The impulsive phase onset is delayed by 10 minutes from the start of the descent, but coincides with the rapid speed increases of the upward plasmoids, the individual loop shrinkages, and the overall loop-top descent, suggestive of an intimate relation of the energy release rate and reconnection outflow speed.

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Section: Proposed Physical Picturementioning

confidence: 99%

Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows

Liu

Chen

Petrosian

2013

ApJ

207

203

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“…If the projection of the magnetic field vector on the line of sight is positive, then the right and left elliptically polarized components correspond to the X and O modes, respectively; otherwise (if the projection is negative), the correspondence is opposite. Note, that even though the emission escaping the data cube is elliptically (not circularly) polarized in a general case, it is implicitly assumed that it then propagates through a coronal plasma with declining values of both electron density and the magnetic field and so the polarization ellipse evolves toward circularity due to the effect of limiting polarization (see, e.g., Zheleznyakov 1997;Fleishman & Toptygin 2013); thus, the emission arriving at the observer is adopted as purely circularly polarized.…”

Section: Radio Emissionmentioning

confidence: 99%

Three-Dimensional Radio and X-Ray Modeling and Data Analysis Software: Revealing Flare Complexity

Nita

Fleishman

Kuznetsov

et al. 2015

ApJ

Self Cite

109

104

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Many problems in solar physics require analysis of imaging data obtained in multiple wavelength domains with differing spatial resolution in a framework supplied by advanced three-dimensional (3D) physical models. To facilitate this goal, we have undertaken a major enhancement of our IDL-based simulation tools developed earlier for modeling microwave and X-ray emission. The enhanced software architecture allows the user to (1) import photospheric magnetic field maps and perform magnetic field extrapolations to generate 3D magnetic field models; (2) investigate the magnetic topology by interactively creating field lines and associated flux tubes; (3) populate the flux tubes with user-defined nonuniform thermal plasma and anisotropic, nonuniform, nonthermal electron distributions; (4) investigate the spatial and spectral properties of radio and X-ray emission calculated from the model; and (5) compare the model-derived images and spectra with observational data. The package integrates shared-object libraries containing fast gyrosynchrotron emission codes, IDL-based soft and hard X-ray codes, and potential and linear force-free field extrapolation routines. The package accepts user-defined radiation and magnetic field extrapolation plug-ins. We use this tool to analyze a relatively simple single-loop flare and use the model to constrain the magnetic 3D structure and spatial distribution of the fast electrons inside this loop. We iteratively compute multi-frequency microwave and multi-energy X-ray images from realistic magnetic flux tubes obtained from pre-flare extrapolations, and compare them with imaging data obtained by SDO, NoRH, and RHESSI. We use this event to illustrate the tool's use for the general interpretation of solar flares to address disparate problems in solar physics.

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“…To perform the sequential spectral fit (Bastian et al 2007;Fleishman et al 2009Fleishman et al , 2013Gary et al 2013) we apply a homogeneous source model with constant depth 20 ′′ and area 1600 ′′2 and three unknown free parameters B(t), T (t), and n th (t), the magnetic field, plasma temperature, and density respectively. Selection of the objective function to be forward fit requires some further discussion in this case.…”

Section: Fit To Maxwellian Plasmamentioning

confidence: 99%

“…The radiative cooling time (e.g., Aschwanden 2005) for such a hot plasma (T ∼ 40 MK) is much longer than the observed one, τ ∼ 30 s; thus the conductive cooling is likely to dominate. The conductive cooling time, τ cond ≈ L 2 ρc p /(κ S T 5/2 ) (Eq (4.3.10) in Aschwanden 2005), where L is the loop length, ρ = n e m p is the plasma mass density, for the fully ionized hydrogen ideal gas c p ρ = 5k B n e , where c p = 2γk B /[(γ − 1)m p ] erg/(g·K) is the spe-cific heat, γ = 5/3, and κ S ≈ 9.2 · 10 −7 erg cm −1 s −1 K −7/2 is the Spitzer conductivity coefficient (see, e.g., Aschwanden 2005;Fleishman & Toptygin 2013). Solving for T and substituting known constants, we find T ≃ 3.82 · 10 7 [K] L 6 · 10 9 cm 4/5 n e 10 10 cm −3 2/5 30 s τ…”

Section: A Consistency Checkmentioning

confidence: 99%

Energy Partitions and Evolution in a Purely Thermal Solar Flare

Fleishman¹,

Nita²,

Gary³

2015

ApJ

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This paper presents a solely thermal flare, which we detected in the microwave range from the thermal gyro-and free-free emission it produced. An advantage of analyzing thermal gyro emission is its unique ability to precisely yield the magnetic field in the radiating volume. When combined with observationally-deduced plasma density and temperature, these magnetic field measurements offer a straightforward way of tracking evolution of the magnetic and thermal energies in the flare. For the event described here, the magnetic energy density in the radioemitting volume declines over the flare rise phase, then stays roughly constant during the extended peak phase, but recovers to the original level over the decay phase. At the stage where the magnetic energy density decreases, the thermal energy density increases; however, this increase is insufficient, by roughly an order of magnitude, to compensate for the magnetic energy decrease. When the magnetic energy release is over, the source parameters come back to nearly their original values. We discuss possible scenarios to explain this behavior.

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Cosmic Electrodynamics

Cited by 40 publications

References 198 publications

Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows

Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows

Three-Dimensional Radio and X-Ray Modeling and Data Analysis Software: Revealing Flare Complexity

Energy Partitions and Evolution in a Purely Thermal Solar Flare

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