Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ornstein-Uhlenbeck parameter extraction from light curves of Fermi-LAT
  observed blazars   Context. Monthly-binned gamma-ray light curves of 236 bright gamma-ray
sources, particularly blazars, selected from a sample of 2278 high-galactic
latitude objects observed with Fermi-LAT, show flux variability characterized
by power spectral densities consisting of a single power-law component, ranging
from Brownian to white noise. Aims. The main goal here is to assess the
Ornstein-Uhlenbeck (OU) model by studying the range of its three parameters
that reproduces these statistical properties. Methods. We develop procedures
for extracting values of the three OU model parameters (mean flux, correlation
length, and random amplitude) from time series data, and apply them to compare
numerical integrations of the OU process with the Fermi-LAT data. Results. The
OU process fully describes the statistical properties of the flux variations of
the 236 blazars. The distributions of the extracted OU parameters are narrowly
peaked about well-defined values (sigma, mu, theta) = (0.2, -8.4, 0.5) with
variances (0.004, 0.07, 0.13). The distributions of rise and decay time scales
of flares in the numerical simulations, i.e. major flux variations fulfilling
pre-defined criteria, are in agreement with the observed ones. The power
spectral densities of the synthetic light curves are statistically
indistinguishable from those of the measured light curves. Conclusions.
Long-term gamma-ray flux variability of blazars on monthly time scales is well
described by a stochastic model involving only three parameters. The methods
described here are powerful tools to study randomness in light curves and
thereby constrain the physical mechanisms responsible for the observed flux
variations.

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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: alg-geom