COMBINED MODELING OF ACCELERATION, TRANSPORT, AND HYDRODYNAMIC RESPONSE IN SOLAR FLARES. I. THE NUMERICAL MODEL
- Stanford-Lockheed Institute for Space Research, 466 Via Ortega, Cypress Hall, Stanford, CA 94305-4085 (United States)
- Department of Physics, Stanford University, Stanford, CA 94305-4060 (United States)
- Naval Research Laboratory, Code 7673, Washington, DC 20375-5000 (United States)
Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self-consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a {approx}10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a nonthermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.
- OSTI ID:
- 21335977
- Journal Information:
- Astrophysical Journal, Vol. 702, Issue 2; Other Information: DOI: 10.1088/0004-637X/702/2/1553; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ANALYTICAL SOLUTION
APPROXIMATIONS
ASTROPHYSICS
BREMSSTRAHLUNG
CHROMOSPHERE
COLLISIONAL HEATING
EVAPORATION
FOKKER-PLANCK EQUATION
GAMMA RADIATION
HEATING RATE
HYDRODYNAMICS
PHOTONS
PLASMA
PLASMA ACCELERATION
SIMULATION
SOLAR FLARES
SPATIAL DISTRIBUTION
SPECTRA
STOCHASTIC PROCESSES
SUN
TAIL ELECTRONS
TELESCOPES
THERMAL CONDUCTION