Gap-type particle acceleration in the magnetospheres of rotating supermassive black holes. (arXiv:2005.05076v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Katsoulakos_G/0/1/0/all/0/1">Grigorios Katsoulakos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rieger_F/0/1/0/all/0/1">Frank M. Rieger</a>
The detection of rapidly variable gamma-ray emission in Active Galactic
Nuclei (AGN) has generated renewed interest in magnetospheric particle
acceleration and emission scenarios. In order to explore its potential, we
study the possibility of steady gap acceleration around the null surface of a
rotating black hole magnetosphere. We employ a simplified (1D) description
along with the general relativistic expression of Gauss’s law, and assume that
the gap is embedded in the radiation field of a radiatively inefficient
accretion flow. The model is used to derive expressions for the radial
distribution of the parallel electric field component, the electron and
positron charge density, the particle Lorentz factor and the number density of
$gamma$-ray photons. We integrate the set of equations numerically, imposing
suitable boundary conditions. The results show that the existence of a steady
gap solution for a relative high value of the global current is in principle
possible if charge injection of both species is allowed at the boundaries. We
present gap solutions for different choices of the global current and the
accretion rate. When put in context our results suggest that the variable
very-high-energy $gamma$-ray emission in M87 could be compatible with a
magnetospheric origin.
The detection of rapidly variable gamma-ray emission in Active Galactic
Nuclei (AGN) has generated renewed interest in magnetospheric particle
acceleration and emission scenarios. In order to explore its potential, we
study the possibility of steady gap acceleration around the null surface of a
rotating black hole magnetosphere. We employ a simplified (1D) description
along with the general relativistic expression of Gauss’s law, and assume that
the gap is embedded in the radiation field of a radiatively inefficient
accretion flow. The model is used to derive expressions for the radial
distribution of the parallel electric field component, the electron and
positron charge density, the particle Lorentz factor and the number density of
$gamma$-ray photons. We integrate the set of equations numerically, imposing
suitable boundary conditions. The results show that the existence of a steady
gap solution for a relative high value of the global current is in principle
possible if charge injection of both species is allowed at the boundaries. We
present gap solutions for different choices of the global current and the
accretion rate. When put in context our results suggest that the variable
very-high-energy $gamma$-ray emission in M87 could be compatible with a
magnetospheric origin.
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