Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Origin of Matter at the Base of Relativistic Jets in Active Galactic
  Nuclei   The generation of relativistic jets in active sources such as blazars is a
complex problem with many aspects, most of them still not fully understood.
Relativistic jets are likely produced by the accretion of matter and magnetic
fields onto spinning black holes. Ergospheric dragging effects launch a
Poynting-dominated outflow in the polar directions of these systems.
Observations with very high resolution of the jet in the nearby radio galaxy
M87 and evidence of extremely fast variability in the non-thermal radiation of
several other objects indicate that charged particles produce synchrotron
emission and gamma rays very close to the base of the jet. How these particles
are injected into the magnetically shielded outflow is a mystery. Here we
explore the effects of various processes in the hot accretion inflow close to
the black hole that might result in the copious production of neutral particles
which, through annihilation and decay in the jet's funnel, might load the
outflow with mass and charged particles on scales of a few Schwarzschild radii.

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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin