Monte Carlo simulations of nuclear processes during solar flares in a magneto active plasma
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Tese
Date
2021-02-10
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Authors
Serra, Jordi Tuneu
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Castro, Guillermo Giménez de
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Raulin, Jean- Pierre
Simões, Paulo José Aguiar
MacKinnon, Alexander
Pazianotto, Maurício Tizziani
Simões, Paulo José Aguiar
MacKinnon, Alexander
Pazianotto, Maurício Tizziani
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Ciências e Aplicações Geoespaciais
Abstract
Solar flares are explosive phenomena involving the energy release of 1027 to 1032
erg in the solar atmosphere in tens of seconds to tens of minutes, manifested as
emission of radiation nearly over the entire electromagnetic spectrum, sometimes
associated with mass motions involving the escape of energetic particles. We do
not yet completely understand the precise mechanisms by which energy is stored
in the magnetic field loops above active regions and suddenly released. Moreover,
we do not fully understand the mechanism that accelerates particles. Nonetheless,
we know that magnetic reconnection in tenuous plasmas plays a key role. Monte
Carlo simulations including magnetic fields become computationally impractical in
the solar flare context since the length of the magnetic loops, thousands of km, is
several orders of magnitude larger than the gyroradius of the particles involved,
from cm to m depending on the particle species and the magnetic field strength. To
address this problem we have written a new module for the Geant4 package using
the Guiding Centre (GC) approach, in which the particle motion is averaged over a
gyrofrequency. We describe the formulation and implementation of this method, in
particular dealing with the uncertainty in the gyrophase so that particle velocities
are well-defined for input to the Geant4 modules handling reactions. The modelling
of secondary particle production by energetic ions in the presence of magnetic fields
within the GC approach, which allows to reduce the runtime of simulations from two
to five orders of magnitude compared to the standard Newton-Lorentz approach,
will provide a framework for interpreting the detailed observations expected from
leading-edge instruments such as ALMA and LLAMA, as well as existing gammaray
measurements from the Fermi satellite and earlier experiments.
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Keywords
erupções solares , processos nucleares de alta energia , pósitrons secundários e elétrons , raios gama , campo magnético , centro guia
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Citation
SERRA, Jordi Tuneu. Monte Carlo simulations of nuclear processes during solar flares in a magneto active plasma. 2021. 119 f. Tese( Ciências e Aplicações Geoespaciais) - Universidade Presbiteriana Mackenzie, São Paulo.