Particle Acceleration and Heating in Regions of Magnetic Flux Emergence. (arXiv:1907.04296v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Isliker_H/0/1/0/all/0/1">Heinz Isliker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Archontis_V/0/1/0/all/0/1">Vasilis Archontis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vlahos_L/0/1/0/all/0/1">Loukas Vlahos</a>
The interaction between emerging and pre-existing magnetic fields in the
solar atmosphere can trigger several dynamic phenomena, such as eruptions and
jets. A key element during this interaction is the formation of large scale
current sheets and, eventually, their fragmentation that leads to the creation
of a strongly turbulent environment. In this paper, we study the kinetic
aspects of the interaction (reconnection) between emerging and ambient magnetic
fields. We show that the statistical properties of the spontaneously fragmented
and fractal electric fields are responsible for the efficient heating and
acceleration of charged particles, which form a power law tail at high energies
on sub-second time scales. A fraction of the energized particles escapes from
the acceleration volume, with a super-hot component with temperature close to
$150,$MK, and with a power law high energy tail with index between -2 and -3.
We estimate the transport coefficients in energy space from the dynamics of the
charged particles inside the fragmented and fractal electric fields, and the
solution of a fractional transport equation, as appropriate for a strongly
turbulent plasma, agrees with the test particle simulations. We also show that
the acceleration mechanism is not related to Fermi acceleration, and the Fokker
Planck equation is inconsistent and not adequate as a transport model. Finally,
we address the problem of correlations between spatial transport and transport
in energy space. Our results confirm the observations reported for high energy
particles (hard X-rays, type III bursts and solar energetic particles) during
the emission of solar jets.
The interaction between emerging and pre-existing magnetic fields in the
solar atmosphere can trigger several dynamic phenomena, such as eruptions and
jets. A key element during this interaction is the formation of large scale
current sheets and, eventually, their fragmentation that leads to the creation
of a strongly turbulent environment. In this paper, we study the kinetic
aspects of the interaction (reconnection) between emerging and ambient magnetic
fields. We show that the statistical properties of the spontaneously fragmented
and fractal electric fields are responsible for the efficient heating and
acceleration of charged particles, which form a power law tail at high energies
on sub-second time scales. A fraction of the energized particles escapes from
the acceleration volume, with a super-hot component with temperature close to
$150,$MK, and with a power law high energy tail with index between -2 and -3.
We estimate the transport coefficients in energy space from the dynamics of the
charged particles inside the fragmented and fractal electric fields, and the
solution of a fractional transport equation, as appropriate for a strongly
turbulent plasma, agrees with the test particle simulations. We also show that
the acceleration mechanism is not related to Fermi acceleration, and the Fokker
Planck equation is inconsistent and not adequate as a transport model. Finally,
we address the problem of correlations between spatial transport and transport
in energy space. Our results confirm the observations reported for high energy
particles (hard X-rays, type III bursts and solar energetic particles) during
the emission of solar jets.
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