Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intrinsic Variability and Field Statistics for the Vela Pulsar: 3.
  Two-Component Fits and Detailed Assessment of Stochastic Growth Theory   The variability of the Vela pulsar (PSR B0833-45) corresponds to well-defined
field statistics that vary with pulsar phase, ranging from Gaussian intensity
statistics off-pulse to approximately power-law statistics in a transition
region and then lognormal statistics on-pulse, excluding giant micropulses.
These data are analyzed here in terms of two superposed wave populations, using
a new calculation for the amplitude statistics of two vectorially-combined
transverse fields. Detailed analyses show that the approximately power-law and
lognormal distributions observed are fitted well at essentially all on-pulse
phases by Gaussian-lognormal and double-lognormal combinations, respectively.
These good fits, plus the smooth but significant variations in fit parameters
across the source, provide strong evidence that the approximately power-law
statistics observed in the transition region are not intrinsic. Instead, the
data are consistent with normal pulsar emission having lognormal statistics at
all phases. This is consistent with generation in an inhomogeneous source
obeying stochastic growth theory (SGT) and with the emission mechanism being
purely linear (either direct or indirect). A nonlinear mechanism is viable only
if it produces lognormal statistics when suitably ensemble-averaged. Variations
in the SGT fit parameters with phase imply that the radiation is relatively
more variable near the pulse edges than near the center, as found in earlier
work. In contrast, Vela's giant micropulses come from a very restricted phase
range and have power-law statistics with indices ($6.7 \pm 0.6$) not
inconsistent with nonlinear wave collapse. These results imply that normal
pulses have a different source and generation mechanism than giant micropulses,
as suggested previously on other grounds.

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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph