Electron Energization in Quasi-Parallel Shocks: Test-Particle-Electrons in a Proton Driven Turbulence. (arXiv:2007.06478v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Hanusch_A/0/1/0/all/0/1">Adrian Hanusch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liseykina_T/0/1/0/all/0/1">Tatyana Liseykina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malkov_M/0/1/0/all/0/1">Mikhail Malkov</a>
In situ observations of energetic particles at the Earth’s bow-shock that are
attainable by the satellite missions have long created the opinion that
electrons are most efficiently accelerated in a quasi-perpendicular shock
geometry. However, shocks that are deemed to be responsible for the production
of cosmic ray electrons and their radiation from sources such as supernova
remnants are much more powerful and larger than the Earth’s bow-shock. Their
remote observations and in situ measurements at Saturn’s bow shock, suggest
that electrons are accelerated very efficiently in the quasi-parallel shocks as
well. In this paper we investigate the possibility that protons that are
accelerated to high energies create sufficient wave turbulence, which is
necessary for the electron preheating and subsequent injection into the
diffusive shock acceleration in a quasi-parallel shock geometry. An additional
test-particle-electron population, which is meant to be a low-density addition
to the electron core-distribution on which the hybrid simulation operates, is
introduced. We investigate how these electrons are energized by the hybrid
electromagnetic field. The reduced spatial dimensionality allowed us to
dramatically increase the number of macro-ions per numerical cell and achieve
the converged results for the velocity distributions of test electrons. We
discuss the electron preheating mechanisms, which can make a significant part
of thermal electrons accessible to the ion-driven waves observed in hybrid
simulations. We find that the precursor wave field supplied by ions has a
considerable potential to preheat the electrons before they are shocked at the
subshock.
In situ observations of energetic particles at the Earth’s bow-shock that are
attainable by the satellite missions have long created the opinion that
electrons are most efficiently accelerated in a quasi-perpendicular shock
geometry. However, shocks that are deemed to be responsible for the production
of cosmic ray electrons and their radiation from sources such as supernova
remnants are much more powerful and larger than the Earth’s bow-shock. Their
remote observations and in situ measurements at Saturn’s bow shock, suggest
that electrons are accelerated very efficiently in the quasi-parallel shocks as
well. In this paper we investigate the possibility that protons that are
accelerated to high energies create sufficient wave turbulence, which is
necessary for the electron preheating and subsequent injection into the
diffusive shock acceleration in a quasi-parallel shock geometry. An additional
test-particle-electron population, which is meant to be a low-density addition
to the electron core-distribution on which the hybrid simulation operates, is
introduced. We investigate how these electrons are energized by the hybrid
electromagnetic field. The reduced spatial dimensionality allowed us to
dramatically increase the number of macro-ions per numerical cell and achieve
the converged results for the velocity distributions of test electrons. We
discuss the electron preheating mechanisms, which can make a significant part
of thermal electrons accessible to the ion-driven waves observed in hybrid
simulations. We find that the precursor wave field supplied by ions has a
considerable potential to preheat the electrons before they are shocked at the
subshock.
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