Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relentless multi-wavelength variability of Mrk 421 and Mrk 501   Mrk 421 and Mrk 501 are two close, bright and well-studied
high-synchrotron-peaked blazars, which feature bright and persistent GeV and
TeV emission. We use the longest and densest dataset of unbiased observations
of these two sources, obtained at TeV and GeV energies during five years with
FACT and Fermi-LAT. To characterize the variability and derive constraints on
the emission mechanism, we augment the dataset with contemporaneous
multi-wavelength observations from radio to X-rays. We correlate the light
curves, identify individual flares in TeV energies and X-rays, and look for
inter-band connections, which are expected from the shock propagations within
the jet. For Mrk 421, we find that the X-rays and TeV energies are well
correlated with close to zero lag, supporting the SSC emission scenario. The
timing between the TeV, X-ray flares in Mrk 421 is consistent with periods
expected in the case of Lense-Thirring precession of the accretion disc. The
variability of Mrk 501 on long-term periods is also consistent with SSC, with a
sub-day lag between X-rays and TeV energies. Fractional variability for both
blazars shows a two bump structure with the highest variability in the X-ray
and TeV bands.

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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
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The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
3
The categories of this paper are: physics