Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray timing and spectral variability properties of blazars S5 0716+714,
  OJ 287, Mrk 501, and RBS 2070   The X-ray emission from blazars has been widely investigated using several
space telescopes. In this work, we explored statistical properties of the X-ray
variability in the blazars S5 0716+714, OJ 287, Mkn 501 and RBS 2070 using the
archival observations from the XMM-Newton telescope between the period
2002-2020. Several methods of timing and spectral analyses including fractional
variability, minimum variability timescale, power spectral density analyses and
countrate distribution were performed. In addition, we fitted various spectral
models to the observations as well as estimated hardness ratio. The results
show that the sources are moderately variable within the intra-day timescale.
Three of the four sources exhibited a clear bi-modal pattern in their countrate
distribution revealing possible indication of two distinct countrate states,
that is, hard and soft countrate states. The slope indices of the power
spectral density were found to be centered around 0.5. Furthermore, the spectra
of the sources were fitted with single power-law, broken power-law,
log-parabolic and black-body+log-parabolic models (the latter only for OJ 287).
We conclude that for most of the observations log-parabolic model was the best
fit. The power spectral density analysis revealed the variable nature of PSD
slopes in the source light curves. The results of this analysis could indicate
the non-stationary nature of the blazar processes on intra-day timescales. The
observed features can be explained within the context of current blazar models,
in which the non-thermal emission mostly arises from kilo-parsec scale
relativistic jets.

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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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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: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin