Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Oscillating pulsar polar gaps   An analytical model for oscillating pair creation above the pulsar polar cap
is presented in which the parallel electric field is treated as a large
amplitude, superluminal, electrostatic wave. An exact formalism for such wave
is derived in one-dimension and applied to both the low-density regime in which
the pair plasma density is much lower than the corotating charge density and
the high-density regime in which the pair plasma density is much higher than
the corotating charge density. In the low-density regime, which is relevant
during the phase leading to a pair cascade, a parallel electric field develops
resulting in rapid acceleration of particles. The rapid acceleration leads to
bursts of pair production and the system switches to the oscillatory phase,
corresponding to the high density regime, in which pairs oscillate with net
drift motion in the direction of wave propagation. Oscillating pairs lead to a
current that oscillates with large amplitude about the Goldreich-Julian
current. The drift motion can be highly relativistic if the phase speed of
large amplitude waves is moderately higher than the speed of light. Thus, the
model predicts a relativistic outflow of pairs, a feature that is required for
avoiding overheating of the pulsar polar cap and is also needed for the pulsar
wind.

16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc