Swift observations of Mrk,421 in selected epochs. iii. Extreme x-ray timing/spectral properties and multiwavelength lognormality in 2015,December–2018,April. (arXiv:2004.00676v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kapanadze_B/0/1/0/all/0/1">B. Kapanadze</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gurchumelia_A/0/1/0/all/0/1">A. Gurchumelia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dorner_D/0/1/0/all/0/1">D. Dorner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vercellone_S/0/1/0/all/0/1">S. Vercellone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Romano_P/0/1/0/all/0/1">P. Romano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hughes_P/0/1/0/all/0/1">P. Hughes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aller_M/0/1/0/all/0/1">M. Aller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aller_H/0/1/0/all/0/1">H. Aller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kharshiladze_O/0/1/0/all/0/1">O. Kharshiladze</a>
We present the results from the timing and spectral study of Mrk,421 based
mainly on the emph{Swift} data in the X-ray energy range obtained during the
time interval 2015,December–2018,April. The most extreme X-ray flaring
activity on the long-term, daily and intraday timescales was observed during
the 2-month period which started in 2017,December when the 0.3–10,keV flux
exceeded a level of 5$times$10$^{-9}$erg,cm$^{-2}$s$^{-1}$, recorded only
twice previously. While the TeV-band and X-ray variabilities mostly were
correlated, the source often varied in a complex manner in the MeV–GeV and
radio–UV energy ranges, indicating that the multifrequency emission of
Mrk,421 could not be always generated in a single zone. The longer-term flares
at X-rays and $gamma$-rays showed a lognormal character, possibly indicating a
variability imprint of the accretion disk onto the jet. A vast majority of the
0.3–10,keV spectra were consistent with the log-parabolic model, showing
relatively low spectral curvature and correlations between the different
spectral parameters, predicted in the case of the first and second-order Fermi
processes. The position of the synchrotron spectral energy distribution (SED)
peak showed an extreme variability on diverse timescales between the energies
$E_{rm p}$$<$0.1,keV and $E_{rm p}$$>$15,keV, with 15% of the spectra
peaking at hard X-rays and was related to the peak height as $S_{rm
p}$$varpropto$$E^{alpha}_{rm p}$ with $alpha$$sim$0.6, which is expected
for the transition from Kraichnan-type turbulence into the textquotedblleft
hard-spheretextquotedblright~ one. The 0.3–300,GeV spectra showed the
features of the hadronic contribution, jet-star interaction and upscatter in
the Klein-Nishina regime in different time intervals.
We present the results from the timing and spectral study of Mrk,421 based
mainly on the emph{Swift} data in the X-ray energy range obtained during the
time interval 2015,December–2018,April. The most extreme X-ray flaring
activity on the long-term, daily and intraday timescales was observed during
the 2-month period which started in 2017,December when the 0.3–10,keV flux
exceeded a level of 5$times$10$^{-9}$erg,cm$^{-2}$s$^{-1}$, recorded only
twice previously. While the TeV-band and X-ray variabilities mostly were
correlated, the source often varied in a complex manner in the MeV–GeV and
radio–UV energy ranges, indicating that the multifrequency emission of
Mrk,421 could not be always generated in a single zone. The longer-term flares
at X-rays and $gamma$-rays showed a lognormal character, possibly indicating a
variability imprint of the accretion disk onto the jet. A vast majority of the
0.3–10,keV spectra were consistent with the log-parabolic model, showing
relatively low spectral curvature and correlations between the different
spectral parameters, predicted in the case of the first and second-order Fermi
processes. The position of the synchrotron spectral energy distribution (SED)
peak showed an extreme variability on diverse timescales between the energies
$E_{rm p}$$<$0.1,keV and $E_{rm p}$$>$15,keV, with 15% of the spectra
peaking at hard X-rays and was related to the peak height as $S_{rm
p}$$varpropto$$E^{alpha}_{rm p}$ with $alpha$$sim$0.6, which is expected
for the transition from Kraichnan-type turbulence into the textquotedblleft
hard-spheretextquotedblright~ one. The 0.3–300,GeV spectra showed the
features of the hadronic contribution, jet-star interaction and upscatter in
the Klein-Nishina regime in different time intervals.
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